高等数学-ALL
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大学高等数学完整整理,考研专用
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微积分及其应用
基本概念
极限<br>
定义与性质
定义:<br>1. 数列的极限;<br>2. 一元函数的极限;<br>3. 二元函数的极限的定义:<br><span style="font-weight: normal;">(3.1)二元函数在某点的极限为A,等价于,对于所有的正数ε,存在整数δ,使得当两点之间的距离小于δ时,总有|f(x,y) - A|<ε;<br>(3.2)极限和无穷小的关系:若函数的极限趋于A,则函数为A与一个无穷小量的和。</span><br>性质:<br>1. 数列极限的基本性质:<span style="font-weight: normal;">极限的不等式性质、收敛数列的有界性</span><br>2. 一元函数极限的基本性质:<span style="font-weight: normal;">极限的不等式性质、极限的保号性、存在极限的函数局部有界性<br></span>3. 二元函数与一元函数有相同的极限运算法则与极限性质<br><span style="font-weight: normal;">(1)直接用极限运算法则;(2)通过适当放大缩小法;(3)变量替换法转换为求简单的极限或一元函数的极限;</span><span style="font-weight: normal;"><br></span>
极限存在性的判别
1. 极限存在的两个准则:<br><span style="font-weight: normal;">(1)夹逼定理;<br>(2)单调有界数列必收敛</span><br>2. 极限存在的一个充要条件:<br><span style="font-weight: normal;">(1)</span>一元函数:<span style="font-weight: normal;">左右极限存在且相等;<br>(2)</span>二元函数:<span style="font-weight: normal;">当点在定义域内沿任何路径以任何方式趋于目标点时,函数的极限均存在且相等,则称二元函数极限存在。<br> 若两条路径下函数的极限值不相等或某一条路径极限不存在,则可断言极限不存在。</span><br><span style="font-weight: normal;">(3)</span>数列:<span class="equation-text" contenteditable="false" data-index="0" data-equation="\lim\limits_{n\to\infin}x_n=A\rightleftarrows\lim\limits_{n\to\infin}x_{2n}=\lim\limits_{n\to\infin}x_{2n-1}=A"><span></span><span></span></span><br>4. 证明极限不存在的常用方法:<br><span style="font-weight: normal;">(1)函数左极限不等于右极限;<br>(2)两个可作为函数自变量的数列,若使得函数的极限不存在或不相等,则函数极限不存在;<br>(3)f(x)在x0处的极限为A,g(x)的不存在,则f(x)+g(x)的不存在,若A≠0,则f(x)g(x)的极限不存在</span><br>
求极限的方法
函数极限
基本方法
1. 四则运算及其推广和幂指数运算及其推广;<br>2. 利用函数连续性;<br>3. 利用变量替换法与重要极限求极限:<br><span class="equation-text" data-index="0" data-equation="(1)\lim\limits_{x\to0}\frac{sinx}{x}=1;" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(2)\lim\limits_{x\to\infin}(1+\frac{1}{x})^x=e(或\lim\limits_{x\to\infin}(1+x)^\frac{1}{x}=e,\lim\limits_{x\to\infin}\frac{ln(1+x)}{x}=1);" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="(3)\lim\limits_{x\to0}x^{x}=1;" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="3" data-equation="(4)\lim\limits_{x\to+\infin}x^\frac{1}{x}=1;" contenteditable="false"><span></span><span></span></span><br>4. 利用等价无穷小因子替换求极限;<br>5. 利用洛必达法则求极限;<br>6. 分别按照定义求左右极限求得函数极限;<br>7. 利用导数定义求极限;<br>
未定式
1. 利用泰勒公式求未定式的极限;
2. <span class="equation-text" contenteditable="false" data-index="0" data-equation="\frac{0}{0},\frac{\infin}{\infin},0·\infin,\infin-\infin,1^\infin,0^0,\infin^0"><span></span><span></span></span>
数列极限
递归数列
1. 先证明递归数列的符合单调有界性【单调有界数列收敛定理】,然后设极限为A带入递归数列中求解即可<br>2. 先设极限为A带入递归数列求解,然后再用适当方法证明。<br>注:函数在区间<i>I</i>单调上升,a2>a1(a2<a1),则数列{an}单调上升(单调下降);若函数单调下降,则数列不具有单调性。
n项和的数列
1. 利用定积分求某些n项和式的极限;<br>2. 适当放大缩小法;<br>3. 利用数值级数求和的方法直接求极限;
n项积的数列
1. 取对数后变成n项和数的数列。
一般情形
1. 通过恒等变形化为可用极限四则运算法则的情形;<br>2. 利用函数极限求数列极限;<br>3. 利用适当放大缩小法求极限;<br>(1)简单的放大缩小手段;<br>(2)利用极限的不等式性质进行放大或缩小<br>
无穷小分析
无穷小、极限、无穷大及其联系
数列的无穷小(量)、函数的无穷小(量)、数列无穷大(量)、函数无穷大(量)<br>无穷小与极限的关系:<span class="equation-text" contenteditable="false" data-index="0" data-equation="\lim\limits_{x\to x_0}f(x)=A\leftrightarrows f(x)=A+α(x),其中\lim\limits_{x\to x_0}α(x)=0"><span></span><span></span></span>;<br>无穷小与无穷大的关系:<span class="equation-text" contenteditable="false" data-index="1" data-equation="若f(x)为无穷小且f(x)≠0,则\frac{1}{f(x)}为无穷大;若f(x)为无穷大,则\frac{1}{f(x)}为无穷小"><span></span><span></span></span>
无穷小的运算性质:<br>(1)有限个无穷小的代数和仍为无穷小;<br>(2)有限个无穷小的积仍为无穷小;<br>(3)有界变量与无穷小的乘积亦为无穷小。
无穷小阶的概念
无穷小阶的定义
同阶无穷小、等价无穷小、高阶无穷小
常见的等价分穷小
1. 当x → 0时<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="sinx\sim tanx\sim arcsinx\sim arctanx\sim e^x-1\sim ln(1+x)\sim x"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="1-cosx\sim \frac12x^2,a^x-1\sim xlna(a>0,a≠1),(1+βx)^α-1\sim αβx,"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="(1+x)^{\frac1n}-1\sim \frac{1}{n}x,log_a(1+x)\sim \frac{1}{lna}x(a>0,a≠1)"><span></span><span></span></span>
等价无穷小的重要性质
(1) 无穷小的传递性;<br>(2) 求极限过程中,积、商可用等价无穷小因子替换;<br>(3) <span class="equation-text" contenteditable="false" data-index="0" data-equation="α(x)\sim β(x)(x\to a) \leftrightarrowsα(x)=β(x)+o(β(x))(x\to a)"><span></span><span></span></span>
无穷小阶的比较与确定无穷小的阶的方法
1. 无穷小阶的比较<br>2. 确定无穷小阶的方法<br>(1)利用等价无穷小;(2)待定阶数法;(3)用泰勒公式;(4)利用无穷小阶的运算性质
函数
概念
一元函数:<br><span style="font-weight: normal;">(1)复合函数、反函数和分段函数、函数记号的运算、基本初等函数与其图像、初等函数</span><br>二元函数:<br><span style="font-weight: normal;">(1)二元函数、定义域、值域;<br>(2)空间点集是二元函数的图形,通常它是一张曲面;<br>(3)曲面z=f(x,y)与平面z=C的交线在Oxy平面上的投影曲线称为z=f(x,y)的等高线<br>(4)二元函数的一个自变量变动,另一个自变量固定,或让(x,y)沿某曲线变动,二元函数就转化为了一元函数<br>(5)一元函数中自变量代表直线上的点,有两个变动方向,而在二元函数中,自变量代表平面上的点,有无数个变动的方向</span><br>
性质
连续性
连续性和间断点的相关概念
函数的点连续
<span class="equation-temp"></span>1. 一元函数在x=x0的某个邻域内有定义,且<span class="equation-text" contenteditable="false" data-index="0" data-equation="\lim\limits_{x\to x_0}f(x)=f(x_0),则称f(x)在点x=x_0处连续"><span></span><span></span></span>;<br>2. 一元函数在x=x0的某个邻域内有定义,且<span class="equation-text" data-index="1" data-equation="\lim\limits_{Δx\to 0}[f(x_0+Δx)-f(x_0)]=0,则称f(x)在点x=x_0处连续" contenteditable="false"><span></span><span></span></span>;<br>3. 一元函数在x=x0的某个邻域内有定义,若对任意给定的ε>0,总存在δ>0,使得当<br><span class="equation-text" data-index="2" data-equation="|x-x_0|<δ时,恒有|f(x)-f(x_0)|<ε,则称f(x)在点x=x_0处连续" contenteditable="false"><span></span><span></span></span>。<br>4. 二元函数连续性定义:<span style="font-weight: normal;">若二元函数在某点的极限值存在且等于函数值,则称函数在该点连续;若函数在D上每一点连续,则函数在D上连续。<br></span>5. 左连续
函数的区间连续
1. 函数在开区间任一点连续,则称函数在开区间连续;<br>2. 函数在开区间左端点右连续,在右端点左连续,则称函数在闭区间连续;<br>3. 一、二或多元初等函数在定义区域上连续:<span style="font-weight: normal;">二元初等函数即由自变量为x和自变量为y的初等函数经过有限次四则运算或复合运算而得的二元函数。<br></span>4. 函数在x0连续,等价于函数在x0既左连续又右连续<br>
间断点的定义与分类
<span style="font-weight: normal;">函数在x=x0的空心邻域或单侧空心邻域有定义,且x=x0不是函数的连续点,则称为函数的</span>间断点<span style="font-weight: normal;">。即x=x0处有以下三种情况之一出现:<br>1. 函数在x0的空心邻域有定义,但在x=x0处无定义;<br>2. 函数在x0处的极限不存在;<br>3. 函数在x0处有定义,极限也存在,但极限不等于函数值<br>间断点的分类:<br></span>第一类间断点:<span style="font-weight: normal;">左极限和右极限都存在</span><br> 可去间断点:<span style="font-weight: normal;">左极限等于右极限,但不等于函数值,或函数在此点无定义</span><br> 跳跃间断点:<span style="font-weight: normal;">左极限和右极限不相等;</span><br>第二类间断点:<span style="font-weight: normal;">左极限和右极限至少有一个不存在</span><br> 无穷间断点:<span style="font-weight: normal;">左极限和右极限至少有一个为∞</span><span style="font-weight: normal;"><br></span>
判断连续性与间断点类型的方法
连续性运算法则:<br>(1)连续性的四则运算法则;<br>(2)复合函数的连续性;<br>(3)反函数的连续性。
判断二元函数连续性与一元函数有相同的方法:<br>(1)若函数是初等函数,则它在定义域区间上处处连续;<br>(2)用连续性运算法则;<br>(3)按定义来判断;<br>(4)分别判断左右连续性。
连续函数的性质
1. 一元连续函数的性质:<br>(1)局部保号性;<br>(2)有界闭区间上连续函数的性质:<br>(2.1)有界闭区间上连续函数的有界性;<br>(2.2)有界闭区间上连续函数存在最大、最小值;<br>(2.3)连续函数介值定理(中间值定理);<br>(2.4)连续函数零点存在性定理;<br>(3) 方程式根的存在性——连续函数介值定理的应用。<br>2. 二元连续函数的性质:<br>(1)二元连续函数的局部保号性;<br>(2)最大值最小值定理;<br>(3)中间值定理。<br>
其他性质
一元函数:<span style="font-weight: normal;">奇偶性、周期性、有界性、单调性、凹凸性<br></span>多元函数:<span style="font-weight: normal;">对变量的奇偶性,有界性<br></span>
性态
一元函数性态
一元函数为常数的条件与函数恒等式的证明
1. 函数为常数的充要条件:函数的导数恒等于0;<br>2. 两个函数差为常数的充要条件:导数恒相等;<br>3. 两个函数恒等的充要条件:导数恒相等且存在点使得函数值相等
单调性<span style="font-weight: normal;">充要判别法</span>
1. f(x)在闭区间连续,在开区间可导,则导数≥(≤)0等价于函数在闭区间单调不减(单调不增);<br>2. 同样条件,导数≥(≤)0且在开区间的任意子区间导数不恒等于0;
极值点<span style="font-weight: normal;">的必要条件与充分判别法</span>
必要条件:<span style="font-weight: normal;">导数为0或不存在;</span><br>第一充分判别定理:<span style="font-weight: normal;">f(x)在开区间连续,且在去心邻域内可导,若在驻点两侧导数异号,则取得极值点;</span><br> 几何意义:<span style="font-weight: normal;">f(x)在x=x0两侧单调性改变,则x=x0为极值点;</span><br>第二充分判别定理:<span style="font-weight: normal;">f(x)在驻点处二阶导数大于零则为极小值点,小于零则为极大值点;几何意义同上。</span>
凹凸性<span style="font-weight: normal;">的定义与充要判别法</span>
定义:<span style="font-weight: normal;">f(x)在闭区间连续,在开区间可导,对于开区间任意的x和x0恒有<br></span><span class="equation-text" contenteditable="false" data-index="0" data-equation="f(x_0)+f'(x_0)(x-x_0)>(<)f(x)"><span></span><span></span></span>,<span style="font-weight: normal;">则称f(x)在闭区间上时凸(凹)的。</span><br>几何意义:<span style="font-weight: normal;">曲线上除切点外,任意点在切线的下(上)方,则称曲线时凹(凸)的。</span>
充要判别定理:<span style="font-weight: normal;">f(x)在闭区间连续,在开区间可导,则函数在闭区间时凸(凹)的充要条件时一阶导数在开区间是单调增(减)函数。</span><br>
拐点<span style="font-weight: normal;">的定义与充分判别法</span>
定义:<span style="font-weight: normal;">函数在x0的某邻域内连续,且该点两侧函数的凹凸性相反,则该点为函数的拐点。</span><br>拐点的必要条件:<span style="font-weight: normal;">二阶导数为0或二阶导数不存在</span><br>拐点的充分判别定理一:<span style="font-weight: normal;">函数在开区间连续,在去心邻域二阶可导,且二阶导数在x0两侧反号,则x0为拐点;<br></span>拐点的充分判别定理二:<span style="font-weight: normal;">同样的条件,若函数的二阶导数为0且三阶导数不为0,则该点为拐点。<br></span>
多元函数性态
基本概念
1. 极值(极大值、极小值),极值点(极大值点、极小值点)<br>2. 驻点:偏导数均为0的点
多元函数恒为常数的条件
1. 偏导数在定义域上恒等于0;<br>2. 全微分在定义域上恒等于0;
若函数定义在全平面上,关于x的偏导为0,则函数为y的函数;关于y的偏导为0,则函数为x的函数。
多元函数取得极值的必要条件与充分条件
1. 必要条件:<span style="font-weight: normal;">偏导数均为0</span><br>2. 充分条件:函数在点的某个邻域内连续且具有一阶及二阶连续偏导数,又<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="f'_x(x_0,y_0)=0,f'_y(x_0,y_0)=0,令f'_{xx}(x_0,y_0)=A,f'_{xy}(x_0,y_0)=B,f'_{yy}(x_0,y_0)=C"><span></span><span></span></span>,则<br>(1)<span class="equation-text" contenteditable="false" data-index="1" data-equation="AC-B^2>0时,函数在点(x_0,y_0)取极值,A>0取极小值,A<0取极大值"><span></span><span></span></span>;<br>(2)<span class="equation-text" data-index="2" data-equation="AC-B^2<0时,点(x_0,y_0)不是函数的取极值" contenteditable="false"><span></span><span></span></span>;<br>(3)<span class="equation-text" data-index="3" data-equation="AC-B^2=0时,函数在这个点可能取极值,也可能不取极值(一般还需要用极值定义另作讨论)" contenteditable="false"><span></span><span></span></span>;<br>
条件极值点的必要条件
若f(x, y), g(x, y)在点P0(x0, y0)的某领域有连续的一阶偏导数且条件函数对y的偏导数不为0,<br>若P0是z=f(x, y)在条件平衡φ(x, y)=0下的极值点,则<span class="equation-text" contenteditable="false" data-index="0" data-equation="\begin{cases}f'_x(P_0)+\lambdaφ'_x(P_0)=0\\f'_y(P_0)+\lambdaφ'_y(P_0)=0\\φ(P_0)=0\end{cases}"><span></span><span></span></span>
微积分
微分学
一元函数微分学
概念与性质
<span class="equation-temp"></span>导数的定义与意义<br><span style="font-weight: 400;"></span>
定义:<span style="font-weight: normal;">若因变量增量和自变量增量的比值的极限存在,则称函数在该点可导,这个极限为函数在该点处的导数(或微商)。</span><br><span style="font-weight: normal;">若极限不存在,则函数在该点处不可导或导数不存在。</span><br>几何意义:<span style="font-weight: normal;">增量趋于0-和0+时极限存在,称为函数在该点左、右可导,极限值称为函数在该点处的左、右导数。</span><br>力学意义:<span style="font-weight: normal;">函数在某一点的导数等于曲线在该点切线的斜率;若函数为位移关于时间的函数,则导数为速度。</span>
<span class="equation-temp"></span>微分的定义与意义<br><span style="font-weight: normal;"></span>
<span class="equation-temp"></span>(1)可微的定义:<span class="equation-text" data-index="0" data-equation="函数y=f(x)在点x_0的某邻域内有定义,当自变量有增量\Delta x时,若存在与Δx无关的常数A(x_0),使得函数的增量Δy=f(x_0+\Delta x)-f(x_0)可表为\Delta y=A(x_0)\Delta x+o(\Delta x)(\Delta x\to 0),则称函数在点x=x_0处可微,A(x_0)\Delta x称为函数在点x=x_0处的微分,记作dy|_{(x=x_0)}=A(x_0)\Delta x或df|_{(x=x_0)}=A(x_0)\Delta x。" contenteditable="false"><span></span><span></span></span><br>函数在某点处的微分是该函数在该点处函数增量的线性主要部分(简称,线性主部)<br>(2)微分的几何意义:<span style="font-weight: normal;">Δy为函数相应于自变量增量Δx的纵坐标的增量,微分dy|(x=x0)是曲线在该点处切线相应于自变量增量Δx的纵坐标的增量。</span><br><span style="font-weight: normal;"></span>
可导的充要条件及与可微、连续的联系<br><span style="font-weight: normal;"></span>
<span style="font-weight: normal;">(1)函数在某点可导【等价于】函数在该点左右导数均存在且相等;<br>(2)函数在某点可导【等价于】函数在该点可微;<br>(3)函数在某点可导是函数在该点连续的充分条件;</span>
<span class="equation-temp"></span>函数在区间上的可导性,导函数及高阶导数<br><span style="font-weight: 400;"></span>
(1)函数在区间上的可导性:<span style="font-weight: normal;">函数在开区间上的任意点可导,则函数在开区间可导。另外若函数在左右端点分别右左可导,则函数在闭区间可导<br></span>(2)导函数:<span style="font-weight: normal;">函数在区间I可导,对于区间内任意点都对应着函数的一个确定的导数值,这就构成了一个新的函数,叫做函数的导函数,简称导数(一阶导数)</span><span class="equation-text" data-index="0" data-equation="记作y',f'(x),\frac{dy}{dx},\frac{df(x)}{dx}。" contenteditable="false"><span></span><span></span></span><br>(3)二阶导数及高阶导数:<span style="font-weight: 400;">一阶导数的导数,称为二阶导数</span><span style="font-weight: normal;"></span><span class="equation-text" data-index="1" data-equation="记作y‘',f'’(x),\frac{d^2y}{dx^2},\frac{d^2f(x)}{dx^2}。" contenteditable="false"><span></span><span></span></span><span style="font-weight: 400;">n-1阶导数的导数称为函数的n阶导数,</span><span style="font-weight: normal;"></span><span class="equation-text" data-index="2" data-equation="记作y^{(n)},f^{(n)}(x),\frac{d^ny}{dx^n},\frac{d^nf(x)}{dx^n}。" contenteditable="false"><span></span><span></span></span><br>(4)二阶导数的力学意义:<span style="font-weight: 400;">位移关于时间的函数的二阶导数为加速度函数</span>
奇偶函数与周期函数的导数性质<br><span style="font-weight: 400;"></span>
(1)奇偶函数:<span style="font-weight: normal;">奇函数的导函数为偶函数;偶函数的导函数为奇函数。</span><br>(2)周期函数:<span style="font-weight: 400;">原函数以T为周期,则导函数也以T为周期。</span>
法则
导数的四则运算
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)(u±v)'=u'±v';(2)(uv)'=vu'+uv';(3)(u/v)'=\frac{(vu'-uv')}{v^2}(v≠0)"><span></span><span></span></span>
复合函数的微分法则
一阶微分不变性
计算
按定义求导数及其适用的情形
1. 按照定义求极限:<span style="font-weight: normal;">求函数增量和自变量增量的0/0型极限</span><br>2. 适合用定义求导数的几种情形<br><span style="font-weight: normal;">(2.1)常数函数、某些基本初等函数的导数公式;<br>(2.2)求导法则不能适用的情形</span>【只限定了某个函数连续并没有限定可导】;<br><span style="font-weight: normal;">(2.3)某类分段函数在分界点处的导数。</span><br>3. 利用导数定义求极限<br><span style="font-weight: normal;">(3.1)函数的导函数存在,若所求极限可化为增量比的形式,则极限值为导函数<br>(3.2)若导函数存在,由数列极限与函数极限的关系还可得当</span><span class="equation-text" contenteditable="false" data-index="0" data-equation="\lim\limits_{n\to \infin}x_n=0时,\lim\limits_{n\to \infin}\frac{f(x+x_n)-f(x)}{x_n}=f'(x)"><span></span><span></span></span>
<span class="equation-temp"></span>基本初等导数表<br><span style="font-weight: normal;"></span>
初等函数求导法
适当选择中间变量,将给定的初等函数分解成基本初等函数的复合或四则运算。
几类特殊函数的微分法
<span style="font-weight: normal;"></span>幂指数函数<span class="equation-text" data-index="0" data-equation="f(x)^{g(x)}" contenteditable="false"><span></span><span></span></span>的求导法<br>
<span style="font-weight: normal;">(1.1)将</span><span class="equation-text" data-index="0" data-equation="f(x)^{g(x)}" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">表示成</span><span class="equation-text" data-index="1" data-equation="e^{g(x)lnf(x)}" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">求导;</span><br><span style="font-weight: normal;">(1.2)对数求导法,先取对数再求导</span>
反函数求导法<br>
(2.1)互为反函数的函数的导函数互为倒数(导函数不为零)
由参数方程确定的函数的<br>求导法x=φ(x), y=ψ(x)<br><span style="font-weight: normal;"></span>
<span style="font-weight: normal;">(3.1)</span><span class="equation-text" data-index="0" data-equation="\frac{dy}{dx}=\frac{\psi'(x)}{φ'(x)},\frac{d^2y}{dx^2}=\frac{d}{dx}[\frac{\psi'(x)}{φ'(x)}]=\frac{d}{dt}[\frac{\psi'(x)}{φ'(x)}]\frac{dt}{dx}=\frac{\psi''(t)φ'(t)-\psi'(t)φ''(t)}{φ'^3(t)}" contenteditable="false"><span></span><span></span></span>
隐函数求导法<br><span style="font-weight: normal;"></span>
<span style="font-weight: normal;">(4.1)方程两边同时对自变量求导,然后解出y';<br>(4.2)方程两边同时微分,然后求解dy/dx;<br>(4.3)二元函数F(x, y)=0确定的隐函数y=y(x)的导数公式,</span><span class="equation-text" data-index="0" data-equation="y'(x)=-\frac{F'_x}{F'_y}" contenteditable="false"><span></span><span></span></span>。
变限积分求导法<br><span style="font-weight: 400;"></span>
<span style="font-weight: 400;">(5.1)</span><span class="equation-text" data-index="0" data-equation="\frac{d}{dx}\int_{\psi(x)}^{φ(x)}f(t)dt=f[φ(x)]φ'(x)-f[\psi(x)]\psi'(x)" contenteditable="false"><span></span><span></span></span>,当φ(x),ψ(x)为常数或为自变量本身时为特殊情况
分段函数的求导法
<span style="font-weight: normal;">(6.1) 按照定义求分界点处的左右导数或导数<br>(6.2) 按求导法则分别求分段函数在分界点处的左右导数<br>(6.2.1)若导数存在,则函数在该点的左右导数均存在且相等;<br>(6.2.2)若两个函数在x0的右领域或左邻域函数值相等,则函数在x0具有相同的右或左可导性,可得到如下求分界点处导数的一个方法:<br></span><span class="equation-text" contenteditable="false" data-index="0" data-equation="设\begin{cases}g(x),x_0-\delta<x≤x_0\\h(x),x_0<x<x_0+\delta\end{cases},\delta>0为某常数,若g'_-(x_0)=h'_+(x_0)\overset{记为}{=}A,又g(x_0)=h(x_0),则f'(x_0)=A"><span></span><span></span></span>;<br><span style="font-weight: normal;">(6.3) 分界点是连续点时,求导函数在分界点处的极限值或左、右极限值<br>设函数在x0的某个空心邻域内可导且在x0处连续。若导函数在该点的极限值为A,则该点的导数为A。<br></span>
高阶导数及n阶导数的求法
(7.1)归纳法:<span style="font-weight: normal;">依次求出函数的前几阶导数的表达式,并由此观察规律性,写出n阶导数的公式,再用数学归纳法证明。</span><br>(7.2)利用初等函数的n阶导数公式<br>(7.3)分解法:<br><span style="font-weight: normal;">(7.3.1)有理函数或无理函数的分解<br>(7.3.2)三角函数的分解(利用三角函数恒等式及有关公式)</span><br>(7.4)用莱布尼兹法则求乘积的n阶导数<br><span class="equation-text" data-index="0" data-equation="[u(x)v(x)]^{(n)}=\sum\limits_{k=0}^nC_n^ku^{(k)}(x)v^{(n-k)}(x),C_n^k=\frac{n!}{k!(n-k)!},u^{(0)}(x)=u(x),v^{(0)}(x)=v(x)" contenteditable="false"><span></span><span></span></span><br>(7.5)由函数在x=x0处的泰勒公式的系数或幂级数展开式的系数求n阶导数
微分中值定理
基本概念
极小(大)值点,极小(大)值,极值点,极值,驻点(导数为0的点)
费马定理
<span style="font-weight: normal;">y=f(x)在x=x0处可导且取极值,则f'(x0)=0。f(x)取极值且可导的点称为驻点,反之不成立。</span><br>几何意义:<span style="font-weight: normal;">曲线在极值点处的切线不垂直于x轴,则必平行于x轴。</span>
罗尔定理
<span style="font-weight: normal;">f(x)在闭区间连续,在开区间可导,且在端点的值相等,则开区间内必然存在一个点使得该点的导数为0。</span><br>几何意义:<span style="font-weight: normal;">两点的纵坐标相等,且两点间的每一点都有不垂直于x轴的切线,则必存在一点使得该点切线平行于x轴。</span>
拉格朗日中值定理
<span style="font-weight: normal;">f(x)在闭区间连续,在开区间可导,则存在一点使得该点ξ有f(b)-f(a)=f'(ξ)(b-a)。</span><br><span style="font-weight: normal;">或f(x)=f(x0)+f'(ξ)(x-x0),f(x+Δx) - f(x)=f'(x+θΔx)·Δx,0<θ<1,又称为</span>有限增量定理。<br>几何意义:<br><span style="font-weight: normal;">曲线两点之间每一点都有不垂直于x轴的切线,则曲线在两点间必然存在一点使得该点的切线与两点的割线平行。</span>
柯西中值定理
f(x),g(x)在闭区间上连续,在开区间内可导,且g'(x)≠0,则开区间上必存在一点ξ使得<span class="equation-text" contenteditable="false" data-index="0" data-equation="\frac{f(b)-f(a)}{g(b)-g(a)}=\frac{f‘(ξ)}{g'(ξ)}"><span></span><span></span></span>
泰勒公式
定义
带皮亚诺余项的泰勒公式
<span class="equation-text" contenteditable="false" data-index="0" data-equation="R_n(x)=o((x-x_0)^n)(x→x_0)"><span></span><span></span></span>
带拉格朗日余项的泰勒公式
<span class="equation-text" contenteditable="false" data-index="0" data-equation="R_n(x)=\frac{f^{n+1}(ξ)}{(n+1)!}(x-x_0)^{n+1},ξ在x和x_0之间,也可表为ξ=x_0+θ(x-x_0),0<θ<1"><span></span><span></span></span>
当x0=0时的泰勒公式分别称为带皮亚诺余项与带拉格朗日余项的麦克劳林公式
求法
直接求法
泰勒公式具有唯一性,可通过求解各阶导数构造
间接求法
已知泰勒公式四则运算、变量替换、逐项求导或求积分
五个基本初等函数的麦克劳林公式
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)e^x=\sum^{n}_{k=0}\frac{x^k}{k!}+R_n(x),R_n(x)=o(x^n)(x→0),R_n(x)=\frac{e^{θx}}{(n+1)!}x^{n+1},x\in(-∞, +∞)"><span></span><span></span></span><span class="equation-text" contenteditable="false" data-index="1" data-equation="(2)sinx=\sum^{n}_{k=1}(-1)^{k-1}\frac{x^{2k-1}}{(2k-1)!}+R_{2n}(x),R_{2n}(x)=o(x^{2n})(x→0),R_{2n}(x)=(-1)^n\frac{cosθx}{(2n+1)!}x^{2n+1},x\in(-∞, +∞)"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="(3)cosx=\sum^{n}_{k=0}(-1)^{k}\frac{x^{2k}}{(2k)!}+R_{2n+1}(x),R_{2n+1}(x)=o(x^{2n+1})(x→0),R_{2n+1}(x)=(-1)^{n+1}\frac{cosθx}{(2n+2)!}x^{2n+2},x\in(-∞, +∞)" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="3" data-equation="(4)(1+x)^α=1+\sum^{n}_{k=1}\frac{α(α-1)...(α-k+1)}{k!}x^k+R_{n}(x),R_{n}(x)=o(x^{n})(x→0),R_{n}(x)=\frac{α(α-1)...(α-n)}{(n+1)!}(1+θx)^{α-n-1}x^{n+1},x\in(-∞, +∞)"><span></span><span></span></span><span class="equation-text" contenteditable="false" data-index="4" data-equation="(5)ln(1+x)=\sum_{k=1}^{n}\frac{(-1)^{k-1}x^k}{k}+R_n(x),R_n(x)=o(x^n)(n→0),R_n(x)=\frac{(-1)^nx^{n+1}}{(n+1)(1+θx)^{n+1}}x\in(-1,1]"><span></span><span></span></span>
多元函数微分学
概念与意义
偏导数
概念与几何意义
概念:<br><span style="font-weight: normal;">设有二元函数z=f(x,y),若存在</span><span class="equation-text" data-index="0" data-equation="\frac{d}{dx}f(x,y_0)|_{x=x_0}(\frac{d}{dy}f(x_0,y)|_{y=y_0})" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">,<br>称它为z=f(x,y)在点(x0,y0)处对x(对y)的偏导数,记为</span><span class="equation-text" contenteditable="false" data-index="1" data-equation="\frac{\partial f(x_0,y_0)}{\partial x},\frac{\partial z}{\partial x}|_{(x_0,y_0)},\frac{\partial f}{\partial x}|_{(x_0,y_0)},z^{'}_x|_{(x_0,y_0)}或f^{'}_x(x_0,y_0)"><span></span><span></span></span><span style="font-weight: normal;"><br></span><span class="equation-text" contenteditable="false" data-index="2" data-equation="(\frac{\partial f(x_0,y_0)}{\partial y},\frac{\partial z}{\partial y}|_{(x_0,y_0)},\frac{\partial f}{\partial y}|_{(x_0,y_0)},z^{'}_y|_{(x_0,y_0)}或f^{'}_y(x_0,y_0))"><span></span><span></span></span><span style="font-weight: normal;"><br>按照定义有:<br></span><span class="equation-text" contenteditable="false" data-index="3" data-equation="\frac{\partial f(x_0,y_0)}{\partial x}=\lim\limits_{\Delta x\to0}\frac{f(x_0+\Delta x,y_0)-f(x_0,y_0)}{\Delta x},\frac{\partial f(x_0,y_0)}{\partial y}=\lim\limits_{\Delta y\to0}\frac{f(x_0+\Delta y,y_0)-f(x_0,y_0)}{\Delta y}"><span></span><span></span></span><span style="font-weight: normal;"><br>若函数在区域D的每一点(x,y)处都有偏导数,一般地说,它们仍是x,y的函数,<br>称为函数的偏导函数,简称偏导数,记为</span><span class="equation-text" contenteditable="false" data-index="4" data-equation="\frac{\partial z}{\partial x},\frac{\partial f}{\partial x},f_x^{'}(x,y); \frac{\partial z}{\partial y},\frac{\partial f}{\partial y},f_y^{'}(x,y);"><span></span><span></span></span>
<span style="font-weight: normal;"><span class="equation-temp"></span>1. 若一阶偏导数关于x和y的偏导数仍然存在,则称</span>一阶偏导数的偏导数<span style="font-weight: normal;">是函数的</span>二阶偏导数<span style="font-weight: normal;">;</span><br><span style="font-weight: normal;">2. 对不同自变量求导的高阶偏导数称为</span>混合偏导数<span style="font-weight: normal;">;</span><br><span style="font-weight: normal;"></span><span style="font-weight: normal;"></span>
几何意义:<br><span style="font-weight: normal;">1. 偏导数本质上是一元函数的导数;</span><br><span style="font-weight: normal;">2. </span><span class="equation-text" contenteditable="false" data-index="0" data-equation="\frac{\partial f(x_0,y_0)}{\partial x}"><span></span><span></span></span><span style="font-weight: normal;">即曲面z=f(x,y)与平面y=y0的交线在点M0(x0,y0,f(x0,y0))处的切线对x轴的斜率;<br>3. </span><span class="equation-text" data-index="1" data-equation="\frac{\partial f(x_0,y_0)}{\partial y}" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">即曲面z=f(x,y)与平面x=x0的交线在点M0(x0,y0,f(x0,y0))处的切线对y轴的斜率;</span><br>
性质
<span class="equation-temp"></span>1. 偏导数的连续性:<span style="font-weight: normal;">偏导数在定义域上连续,即极限存在且等数偏导数值;</span><br>2. 可偏导性:<span style="font-weight: normal;">函数在(x0, y0)处存在偏导数,则称函数在该点可偏导;</span><br>3. 二阶偏导数与求导的先后次序无关:<span style="font-weight: normal;">若函数的两个二阶偏导数</span><span class="equation-text" data-index="0" data-equation="\frac{\partial^2z}{\partial x\partial y}和\frac{\partial^2z}{\partial y\partial x}" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">都在区域D上连续,则在区域D内</span><span class="equation-text" data-index="1" data-equation="\frac{\partial^2z}{\partial x\partial y}=\frac{\partial^2z}{\partial y\partial x}" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">。</span>
计算
1. 求偏导数,归结为求一元函数的导数;<br>2. 求<span class="equation-text" contenteditable="false" data-index="0" data-equation="f(x,y)=\begin{cases}g(x,y),(x,y)≠(x_0,y_0)\\A,(x,y=(x_0,y_0))\end{cases}"><span></span><span></span></span>在(x0,y0)处的偏导数的方法<br>(2.1)按照定义<span class="equation-text" contenteditable="false" data-index="1" data-equation="\frac{\partial f(x_0,y_0)}{\partial x}=\lim\limits_{\Delta x\to0}\frac{f(x_0+\Delta x,y_0)-f(x_0,y_0)}{\Delta x}=\lim\limits_{\Delta x\to0}\frac{g(x_0+\Delta x,y_0)-A}{\Delta x};类似地可求\frac{\partial f(x_0,y_0)}{\partial y}"><span></span><span></span></span><br>(2.2)在连续的条件下求偏导数的极限
可微性与全微分
基本概念
1. 全增量:<span class="equation-text" contenteditable="false" data-index="0" data-equation="Δz=f(x_0+Δx,y_0+Δy)-f(x_0,y_0)"><span></span><span></span></span><br>2. 可微:<span style="font-weight: normal;">二元函数在点(x0,y0)的某个邻域内有定义,如果该函数在该点处的全增量可表示为<br></span><span class="equation-text" data-index="1" data-equation="\Delta z=A\Delta x+B\Delta y+o(\rho)(\rho\to0)" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">,其中A,B不依赖于Δx和Δy,而仅与x0,y0有关,</span><span class="equation-text" data-index="2" data-equation="\rho=\sqrt{\Delta x^2+\Delta y^2}" contenteditable="false"><span></span><span></span></span><br>3. 全微分:<span class="equation-text" contenteditable="false" data-index="3" data-equation="AΔx+BΔy,记作dz|_{(x_0,y_0)},df|_{(x_0,y_0)},即dz|_{(x_0,y_0)}=A\Delta x+B\Delta y"><span></span><span></span></span>
可微性的充要条件
1. 必要条件:<span style="font-weight: normal;">两个偏导数均存在,且</span><span class="equation-text" contenteditable="false" data-index="0" data-equation="A=f'_x(x_0,y_0),B=f'_y(x_0,y_0),即有dz|_{(x_0,y_0)}=f'_x(x_0,y_0)dx+f'_y(x_0,y_0)dy"><span></span><span></span></span><br>2. 充分条件:<span style="font-weight: normal;">偏导数存在且,偏导数作为二元函数在点(x0,y0)处连续</span>
梯度与方向导数
方向导数
概念
平面上过点M0(x0, y0)以l=(cosα,cosβ)为方向向量的直线参数方程:x=x0+tcosα,y=y0+tcosβ。<br>z=f(x, y)限制在直线上变化时就变成了一元函数φ(t)=f(x0+tcosα,y0+tcosβ)<br>若存在极限<span class="equation-text" contenteditable="false" data-index="0" data-equation="φ'(0)=\lim\limits_{t\to0}\frac{f(x_0+tcosα,y_0+tcosβ)-f(x_0,y_0)}{t}"><span></span><span></span></span>,称它为z=f(x, y)在点M0(x0, y0)沿方向l的方向导数,记为<br><span class="equation-text" contenteditable="false" data-index="1" data-equation="\frac{\partial f(x_0,y_0)}{\partial l}或\frac{\partial f}{\partial l}|_{(x_0,y_0)}"><span></span><span></span></span>
存在性与计算公式
1. 设二元函数在点M0处可微,则函数在M0点沿任意方向l=(cosα, cosβ)存在方向导数且<span class="equation-text" contenteditable="false" data-index="0" data-equation="\frac{\partial f(x_0,y_0)}{\partial l}=\frac{\partial f(x_0,y_0)}{\partial x}cos\alpha+\frac{\partial f(x_0,y_0)}{\partial y}cos\beta"><span></span><span></span></span><br>用极角表示:l=(cosθ, sinθ),相应的方向导数的计算公式为<span class="equation-text" data-index="1" data-equation="\frac{\partial f(x_0,y_0)}{\partial l}=\frac{\partial f(x_0,y_0)}{\partial x}cos\theta+\frac{\partial f(x_0,y_0)}{\partial y}sin\theta" contenteditable="false"><span></span><span></span></span><br>2. 设三元函数在点M0处可微,则函数在M0点沿任意方向l=(cosα, cosβ, cosγ)存在方向导数且<br><span class="equation-text" data-index="2" data-equation="\frac{\partial f(x_0,y_0,z_0)}{\partial l}=\frac{\partial f(x_0,y_0,z_0)}{\partial x}cos\alpha+\frac{\partial f(x_0,y_0,z_0)}{\partial y}cos\beta+\frac{\partial f(x_0,y_0,z_0)}{\partial z}cos\gamma" contenteditable="false"><span></span><span></span></span><br>
梯度
方向导数的计算公式可改成<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="\frac{\partial f(x_0,y_0)}{\partial \overset{\rightharpoonup}{l}}=(\frac{\partial f(x_0,y_0)}{\partial x},\frac{\partial f(x_0,y_0)}{\partial y})·(cos\alpha,cos\beta)=gradf(x_0,y_0)·\overset{\rightharpoonup}{l}=|gradf(x_0,y_0)|cos<gradf(x_0,y_0),\overset{\rightharpoonup}{l}>"><span></span><span></span></span><br><span style="font-weight: normal;">向量</span><span class="equation-text" data-index="1" data-equation="gradf(x_0,y_0)=(\frac{\partial f(x_0,y_0)}{\partial x},\frac{\partial f(x_0,y_0)}{\partial y})" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">称为</span>z=f(x,y)在点M0的梯度(向量)<br>注:沿梯度方向时,方向导数取最大值<span class="equation-text" contenteditable="false" data-index="2" data-equation="|gradf(x_0,y_0)|"><span></span><span></span></span>。<br>
性质
偏导数的连续性、函数可微性、可偏导性与函数连续性之间的关系
<span style="font-weight: normal;">1. 偏导数连续是函数可微性的充要条件<br>2. 函数可微性是函数连续的充要条件<br>3. 函数可微性是函数可偏导的充要条件<br>4. 函数连续和函数可偏导之间没有联系</span>
微分法则
全微分四则运算法则
<br><span class="equation-text" data-index="0" data-equation="(1)d(u±v)=du±dv;(2)d(cu)=cdu,c为常数;" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(3)d(uv)=vdu+udv;(4)d(u/v)=1/v^2(vdu-udv)(v≠0)" contenteditable="false"><span></span><span></span></span>
多元复合函数的微分法则
一阶全微分形式不变性
(2.1)多元函数与一元函数的复合<br><span class="equation-text" data-index="0" data-equation="设x=x(t),y=y(t),z=z(t)在t可导,u=f(x,y,z)在对应点(x,y,z)=(x(t),y(t),z(t))处可微," contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="则复合函数u=f(x(t),y(t),z(t))在t可导,且\frac{du}{dt}=\frac{\partial f}{\partial x}\frac{\partial x}{\partial t}+\frac{\partial f}{\partial y}\frac{\partial y}{\partial t}+\frac{\partial f}{\partial z}\frac{\partial z}{\partial t},称为全导数。" contenteditable="false"><span></span><span></span></span><br>(2.2)多元函数与多元函数的复合
隐函数微分法
由方程式确定的隐函数求导法
<span style="font-weight: normal;"><span class="equation-temp"></span>1. 由一个方程式确定的一元隐函数求导法</span><br>隐函数存在定理:<span style="font-weight: normal;">如果二元函数F(x,y)=0满足如下的条件:</span><br><span style="font-weight: normal;"><span class="equation-temp"></span>(1)函数F(x, y)在点(x0, y0)某邻域有连续的偏导数;(2)F(x0, y0)=0;(3)</span><span class="equation-text" data-index="0" data-equation="F'_y(x_0,y_0)\not=0" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">;<br>则方程F(x, y)=0在点(x0,y0)某邻域恒能唯一确定一个连续函数y=y(x),它满足y0=y(x0),并有连续的导数,且</span><span class="equation-text" contenteditable="false" data-index="1" data-equation="y'=\frac{dy}{dx}=-\frac{F'_x}{F'_y}"><span></span><span></span></span><span style="font-weight: normal;">;</span>
<span style="font-weight: normal;">2. 由一个方程式确定的二元隐函数求导法</span><br>隐函数存在定理:<span style="font-weight: normal;">如果三元函数F(x,y,z)=0满足如下三个条件:<br></span><span style="font-weight: normal;">(1)函数F(x, y, z)在点(x0, y0, z0)某邻域有连续的偏导数;(2)F(x0, y0, z0)=0;(3)</span><span class="equation-text" data-index="0" data-equation="F'_y(x_0,y_0,z_0)\not=0" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">;<br>则方程F(x, y, z)=0在点(x0,y0,z0)某邻域恒能唯一确定一个连续函数z=z(x, y),它满足z0=z(x0, y0),并有连续的偏导数,且</span><span class="equation-text" data-index="1" data-equation="\frac{\partial z}{\partial x}=-\frac{F'_x}{F'_z},\ \ \frac{\partial z}{\partial y}=-\frac{F'_y}{F'_z}" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;">;<br></span>(2.1)求出方程F(x,y,z)=0确定的隐函数z=z(x,y)的一阶偏导数的方法<br><span style="font-weight: normal;">(1)分别对x,y求偏导,然后求解;(2)两边同时求全微分,然后用可微性的必要条件得到结果;(3)代入公式;</span><br>(2.1)求出方程F(x,y,z)=0确定的隐函数z=z(x,y)的二阶偏导数的方法<br><span style="font-weight: normal;">(1)对一阶偏导数的表达式再求偏导;(2)对</span><span class="equation-text" contenteditable="false" data-index="2" data-equation="F'_x+F'_z\frac{\partial z}{\partial x}=0"><span></span><span></span></span><span style="font-weight: normal;">两边对x求偏导数。</span>
由方程组确定的隐函数求导法
1. 由方程组确定的一元隐函数求导法<br><span style="font-weight: normal;">对方程组中的每个方程应用复合函数求导法则得到关于隐函数导数的方程组,然后求解方程组即可。</span><br>2. 由方程组确定的二元隐函数求导法<br><span style="font-weight: normal;">对方程组中的每个方程应用复合函数求导法则得到关于隐函数偏导数的方程组,然后求解方程组即可。</span><br>
积分学
一元函数积分学
积分分类
不定积分
不定积分和原函数的概念
<span style="font-weight: normal;"></span><span class="equation-text" data-index="0" data-equation="若F'(x)=f(x)或dF(x)=f(x)dx在区间I上成立,则称为F(x)为f(x)在区间I中的一个原函数。" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="f(x)在区间I上的全体原函数称为f(x)在区间I上的不定积分,记为\int f(x)dx。" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="其中\int为积分号,x为积分变量,f(x)为被积函数,f(x)dx为被积表达式。" contenteditable="false"><span></span><span></span></span>
原函数与不定积分的关系
若F(x)为f(x)的一个原函数,则f(x)的不定积分为F(x)+C,其中C为任意常数,称为积分常数
原函数的存在性
(1)原函数存在定理:<span style="font-weight: normal;">若函数在闭区间上连续,则变上限积分函数是被积函数在闭区间上的一个原函数。</span><br><span style="font-weight: normal;"> 若函数在闭区间上有第一类间断点,则被积函数在闭区间上不存在原函数。</span><br>(2)初等函数一定存在原函数<br><span style="font-weight: normal;">初等函数在定义域区间上连续,因而一定存在原函数,但原函数不一定是初等函数;</span>
求不定积分与求微分(导数)互为逆运算
<span style="font-weight: normal;"></span><span class="equation-text" data-index="0" data-equation="(1)已知F(x)=求dF(x)=f(x)dx是微分运算;已知f(x)dx求F(x)使得dF(x)=f(x)dx为积分运算" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;"><br></span><span style="font-weight: normal;"></span><span class="equation-text" data-index="1" data-equation="(2)[\int f(x)dx]'=f(x)或d\int f(x)dx=f(x)dx;\int f'(x)dx=f(x)+C或\int df(x)=f(x)+C" contenteditable="false"><span></span><span></span></span>
不定积分的简单性质
(1)被积函数的和的积分等于被积函数的积分的和;<br>(2)被积函数数乘的积分等于积分的数乘。
<div><span style="font-size: inherit;">定积分</span><br></div>
定积分的定义<span style="font-weight: normal;"></span><br>
<span style="font-weight: normal;"><span class="equation-temp"><span class="equation-temp"></span></span></span><span class="equation-text" data-index="0" data-equation="f(x)在[a, b]上的定积分为\int_a^bf(x)dx=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^nf(\xi_i)\Delta x_i," contenteditable="false"><span></span><span></span></span><br><span style="font-weight: normal;"></span><span class="equation-text" data-index="1" data-equation="其中\lambda=\max\limits_{1≤i≤n}\{\Delta x_i\}.\ \ f(x)在[a, b]上存在定积分,也称f(x)在[a, b]可积。" contenteditable="false"><span></span><span></span></span><br>注意三点:<br><span style="font-weight: normal;">(1)定积分要求被积区间有限、被积函数有界;<br>(2)构造定积分和时,区间的分割与点在小区间中的选取都是任意的;<br>(3)定积分是一个数,其值只与被积函数及积分区间有关,而与积分变量用什么字母无关。</span><br><br>
定积分的几何意义<br>
函数在闭区间上连续,则定积分的几何意义为函数曲线与x轴左右端点的垂线的面积的代数和,函数在x轴上方时取正,下方时取负。
函数可积的充分条件和必要条件<br>
1. 可积的必要条件:<span style="font-weight: normal;">若函数在闭区间上可积,则函数在闭区间上有界;</span><br>2. 可积的充分条件:<span style="font-weight: normal;">以下三类函数可积:</span><br><span style="font-weight: normal;">(1)函数在闭区间上连续;<br>(2)函数在闭区间上有界或只有有限个间断点;<br>(3)函数在闭区间上单调;</span>
基本性质
(1)线性性质:<span style="font-weight: normal;">函数的线性组合的积分等于积分的线性组合</span><br>(2)对区间的可加性;<br>(3)比较定理:<br><span style="font-weight: normal;">(3.1)函数值小于另一个函数,则积分小于另一个积分;<br>(3.2)函数值≥0,则积分≥0;<br>(3.3)积分的绝对值≤函数的绝对值的积分;</span><br><span style="font-weight: normal;">(3.4)</span>估值定理:<span style="font-weight: normal;">函数在闭区间[a, b]连续,函数值∈[m,M],则积分值∈[m(b-a), M(b-a)];</span><br>(4)积分中值定理<br><span class="equation-text" data-index="0" data-equation="设函数f(x)在[a, b]上连续,则在(a, b)内至少存在一点\xi使得\int_a^bf(x)dx=f(\xi)(b-a)" contenteditable="false"><span></span><span></span></span><br>(5)连续非负函数的积分性质<br><span style="font-weight: normal;">设函数f(x)在闭区间上连续,且f(x)≥0且不恒等于0,则积分值大于0;<br>设函数f(x)在闭区间上连续非负且定积分值为0,则函数恒等于0。<br>设函数f(x)在闭区间上连续,且在任意子区间上总有定积分值为0,则在该闭区间上,函数值恒为0</span><br>(6)对称区间上奇偶函数的定积分性质<br><span class="equation-text" data-index="1" data-equation="假定f(x)在[-a,a](a>0)为可积函数或连续函数,则有" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="(1)\begin{cases}\int_{-a}^{a}f(x)dx=2\int_0^af(x)dx,当f(x)为偶函数时\\\int_{-a}^{a}f(x)dx=0,当f(x)为奇函数时\end{cases}" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="3" data-equation="(2)F(x)\overset{记}{=}\int_0^xf(t)dt\begin{cases}在[-a,a]为奇函数,当f(x)为偶函数时\\在[-a,a]为偶函数,当f(x)为奇函数时\end{cases}" contenteditable="false"><span></span><span></span></span><br>(7)周期函数的积分性质<br><span class="equation-text" contenteditable="false" data-index="4" data-equation="假定函数f(x)以T为周期,即对于任意实数x有f(x+T)=f(x),在[0,T]上f(x)可积分(或连续),那么"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="5" data-equation="(1)\int_a^{a+T}f(x)dx=\int_0^Tf(x)dx,即在任意长度为T的区间上的积分值是相等的;"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="6" data-equation="(2)\int_0^xf(t)dt以T为周期的充要条件是\int_0^Tf(t)dt=0;"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="7" data-equation="(3)设连续函数f(x)以T为周期,则f(x)的全体原函数以T为周期的充要条件为\int_0^Tf(t)dt=0"><span></span><span></span></span><br><br>
变限定积分
变限定积分(函数)的连续性与可导性
<span style="font-weight: normal;">(1)设闭区间任意固定的点x0,若函数在闭区间上可积,则变上限积分在闭区间上的连续函数;</span><br><span style="font-weight: normal;">(2)函数在闭区间上连续,则变上限积分是闭区间上的可导函数,且导函数为被积函数;</span><br><span style="font-weight: normal;">(3)函数在闭区间上连续,则变下限积分函数在闭区间上可导,且导函数为负的被积函数;</span><br><span class="equation-text" data-index="0" data-equation="(4)若f(x)在[a, b]上连续,可导函数\phi(x)的定义域为[a, b]且其值域不超过区间[a, b]," contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="则\Phi(x)=\int_a^{\phi(x)}f(t)dt在[a, b]上可导,且\frac{d}{dx}\int_a^{\phi(x)}f(t)dt=f[\phi(x)]\phi'(x)" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="(5)设f(x)在[a, b]上连续,\phi(x),\psi(x)在[\alpha, \beta]可导,当x\in[\alpha, \beta]时,a≤\phi(x),\psi(x)≤b," contenteditable="false"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="3" data-equation="则y=\int_{\psi(x)}^{\phi(x)}f(t)dt在[\alpha, \beta]可导,且\frac{dy}{dx}=\frac{d}{dx}\int^{\phi(x)}_{a}f(t)dt-\frac{d}{dx}\int^{\psi(x)}_{a}f(t)dt=f[\phi(x)]\phi'(x)-f[\psi(x)]\psi'(x)"><span></span><span></span></span>
不定积分与变限积分的关系
<br><span class="equation-text" data-index="0" data-equation="设f(x)在[a, b]上连续,则\int f(x)dx=\int_{x_0}^xf(t)dt+C,C为任意常数,x_0,x\in[a, b],且x_0为某定值" contenteditable="false"><span></span><span></span></span>
反常积分(广义积分)
无穷区间上反常积分的概念
f(x)定义在三种情况下[a, +∞)、(-∞, b]、(-∞, +∞),且在有界闭区间[a, b]上存在定积分,则<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)\int_a^{+\infin}f(x)dx=\lim\limits_{b\to +\infin}\int_a^bf(x)dx"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="(2)\int_{-\infin}^bf(x)dx=\lim\limits_{a\to -\infin}\int_a^bf(x)dx"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="(3)\int_{-\infin}^{+\infin}f(x)dx=\int_{-\infin}^{0}f(x)dx+\int_{0}^{+\infin}f(x)dx=\lim\limits_{a\to -\infin}\int_a^0f(x)dx+\lim\limits_{b\to +\infin}\int_0^bf(x)dx"><span></span><span></span></span><br>若右端极限均存在,称反常积分收敛,否则称为发散。
无界函数的反常积分的概念
如果f(x)在x0的任一邻域都无界,则称x=x0为函数f(x)的瑕点(也称为无界间断点),无界函数的反常积分称为瑕积分。<br>f(x)定义在三种情况下[a+ε, b](在a点的右邻域无界)、[a, b-ε](在b点的右邻域无界)、[a, c-ε]及[c+ε, b](在c点的邻域无界)可积,则<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)\int_a^bf(x)dx=\lim\limits_{\epsilon\to0+}\int_{a+\epsilon}^{b}f(x)dx"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(2)\int_a^bf(x)dx=\lim\limits_{\epsilon\to0+}\int_{a}^{b-\epsilon}f(x)dx" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="(3)\int_a^bf(x)dx=\int_a^cf(x)dx+\int_c^bf(x)dx=\lim\limits_{\epsilon_1\to0+}\int_{a}^{c-\epsilon_1}f(x)dx+\lim\limits_{\epsilon_2\to0+}\int_{c+\epsilon_2}^{b}f(x)dx" contenteditable="false"><span></span><span></span></span><br>若右端极限均存在,称反常积分收敛,否则称为发散
几个常见的反常积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)\int_a^{+\infin}\frac{dx}{x^p}\begin{cases}收敛,p>1,\\发散,p≤1,\end{cases}a>0"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(2)\int_a^{+\infin}\frac{dx}{xln^px}\begin{cases}收敛,p>1,\\发散,p≤1,\end{cases}a>1" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="(3)\int_a^{+\infin}x^ke^{-\lambda x}dx\begin{cases}收敛,\lambda>0,\\发散,\lambda≤0,\end{cases}k≥0" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="3" data-equation="(4)\int_a^{b}\frac{dx}{(x-a)^p}\begin{cases}收敛,p<1,\\发散,p≥1,\end{cases}" contenteditable="false"><span></span><span></span></span><br>
重要公式与运算法则
牛顿-莱布尼兹公式
<span style="font-weight: normal;"><span class="equation-temp"></span><span class="equation-temp"></span><span class="equation-temp"></span>设f(x)在[a,</span> <span style="font-weight: normal;">b]上连续,F(x)是f(x)在[a,</span> <span style="font-weight: normal;">b]上的一个原函数,则</span><span class="equation-text" data-index="0" data-equation="\int_a^bf(x)dx=F(x)|_a^b=F(b)-F(a)" contenteditable="false"><span></span><span></span></span><br>推论如下:<br><span style="font-weight: normal;">(1)F(x)是f(x)在开区间上的一个原函数,上式仍然成立;</span><br>(2)<span style="font-weight: normal;">设f(x)在[a,</span> <span style="font-weight: normal;">b]上连续,F(x)是f(x)在(a,</span> <span style="font-weight: normal;">b)上的一个原函数,又<br></span><span class="equation-text" data-index="1" data-equation="F(a+0)=\lim\limits_{x\to a+0}F(x),F(b-0)=\lim\limits_{x\to b-0}F(x),则\int_a^bf(x)dx=F(x)|_{a+0}^{b-0}=F(b-0)-F(a+0)" contenteditable="false"><span></span><span></span></span><br>(3)<span style="font-weight: normal;">设f(x)在[a,</span> <span style="font-weight: normal;">b]上连续,F(x)在[a,</span> <span style="font-weight: normal;">b]除去c∈(a, b)连续,F(c-0)与F(c+0)存在,且F'(x)=f(x),x∈(a, b),x≠c,则 <br></span><span class="equation-text" data-index="2" data-equation="\int_a^bf(x)dx=F(x)|_a^{c-0}+F(x)|_{c+0}^b=F(b)-F(c+0)+F(c-0)-F(a)" contenteditable="false"><span></span><span></span></span><br>
反常积分运算法则
1. 若原函数的极限存在,则反常积分收敛,且有<span class="equation-text" data-index="0" data-equation="\int_a^{+\infin}f(x)dx=F(x)|_a^{+\infin}=F(+\infin)-F(a)" contenteditable="false"><span></span><span></span></span><br>2. 若两个反常积分收敛,则被积函数的线性组合仍然收敛,且有<span class="equation-text" data-index="1" data-equation="\int_a^{+\infin}[k_1f(x)+k_2g(x)]dx=k_1\int_a^{+\infin}f(x)dx+k_2\int_a^{+\infin}g(x)dx" contenteditable="false"><span></span><span></span></span><br>3. <span class="equation-text" contenteditable="false" data-index="2" data-equation="设f(x),g(x)在[a,+\infin)有连续的导数,若\lim\limits_{x\to+\infin}f(x)g(x)存在,且\int_a^{+\infin}f'(x)g(x)dx收敛,则\int_a^{+\infin}f(x)g'(x)dx收敛,且"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="3" data-equation="\int_a^{+\infin}f(x)g'(x)dx=f(x)g(x)|_a^{+\infin}-\int_a^{+\infin}f'(x)g(x)dx,这里f(x)g(x)|_a^{+\infin}=\lim\limits_{x\to+\infin}[f(x)g(x)]-f(a)g(a)"><span></span><span></span></span><br>4. 设f(x)在[a, +∞)连续,φ(t)在[α,β)有连续的导数且单调,φ(α)=a,<span class="equation-text" contenteditable="false" data-index="4" data-equation="\lim\limits_{t\to\beta-0}φ(t)=+∞,则\int_a^{+\infin}f(x)dx\overset{x=\phi(x)}=\int_\alpha^\beta f[\phi(t)]\phi'(t)dt,这里\beta可以是有限的,也可以为\infin"><span></span><span></span></span>
积分计算
基本积分表<br>
三个扩充<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="\int\frac{dx}{\sqrt{x^2±a^2}}=ln|x+\sqrt{x^2±a^2}|+C"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="\int\sqrt{a^2-x^2}{dx}=\frac{a^2}{2}arcsin\frac{x}{a}+\frac{x}{2}\sqrt{a^2-x^2}+C" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="\int{\sqrt{x^2±a^2}}dx=\frac{x}{2}\sqrt{x^2±a^2}±\frac{a^2}{2}ln|x+\sqrt{x^2±a^2}|+C" contenteditable="false"><span></span><span></span></span><br>
积分法则<br>
分项积分法<br>
将复杂函数分成几个简单函数的和
分段积分法<br>
定积分的分段积分法<br>
不定积分的分段积分法<br>(1)连续拼接法:求得每个分段的原函数,然后使得分界点的函数值连续<br>(2)变限积分法
换元积分法<br>(变量替换法)<br>
不定积分的换元积分法<br>
(1)第一换元积分法(凑微分法)<br><span class="equation-text" data-index="0" data-equation="设\int f(u)du=F(u)+C,且函数\phi(x)可导," contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="则\int f[\phi(x)]\phi'(x)dx=\int f[\phi(x)]d\phi(x)\overset{令u=\phi(x)}{=}\int f(u)du=F(u)+C=F[\phi(x)]+C" contenteditable="false"><span></span><span></span></span><br>(2)第二换元积分法<br><span class="equation-text" contenteditable="false" data-index="2" data-equation="设x=\phi(t)可微,\phi'(t)\not=0,若\int f[\phi(t)]\phi'(t)dt=G(t)+C,则有换元公式"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="3" data-equation="\int f(x)dx=\int f[\phi(t)]\phi'(t)dt=G(t)+C=G[\phi^*(x)]+C,其中t=\phi^*(x)是x=\phi(t)的反函数"><span></span><span></span></span><br>
定积分的换元积分法
函数在闭区间[a, b]连续,若替换关系x=φ(t)满足条件:<br>(1)φ'(t)在[α,β](或[β,α])上连续;<br>(2)φ(α)=a, φ(β)=b,并且当α≤t≤β(或β≤t≤α)时,a≤φ(t)≤b,<br>则<span class="equation-text" contenteditable="false" data-index="0" data-equation="\int_a^bf(x)dx=\int_\alpha^\beta f[\phi(t)]\phi'(t)dt."><span></span><span></span></span>
常用变量替换<br>
三角函数替换<br>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)\sqrt{a^2-x^2}:x=asint,\ -\frac{\pi}{2}≤t≤\frac{\pi}{2}"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(2)\sqrt{a^2+x^2}:x=atant,\ -\frac{\pi}{2}<t<\frac{\pi}{2}" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="(3)\sqrt{x^2-a^2}:x=asect,0≤t≤\pi,t\not=\frac{\pi}{2}"><span></span><span></span></span>
幂函数替换<br>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)\sqrt[n]{ax+b}:t=\sqrt[n]{ax+b}"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(2)\sqrt[n]{\frac{ax+b}{cx+d}}:t=\sqrt[n]{\frac{ax+b}{cx+d}}" contenteditable="false"><span></span><span></span></span><br>
指数函数替换<br>
<span class="equation-text" data-index="0" data-equation="(1)e^x:t=e^x" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(2)a^x:t=a^x" contenteditable="false"><span></span><span></span></span><br>
倒替换
当被积函数的分母的最高次数高于分子的最高次数时,有事可考虑作倒替换<span class="equation-text" contenteditable="false" data-index="0" data-equation="x=\frac1t"><span></span><span></span></span>
分部积分法
不定积分的分部积分法
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\int uv'dx=\int udv=uv-\int u'vdx=\int vdu"><span></span><span></span></span>
定积分的分部积分法
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\int_a^buv'dx=uv|_a^b-\int_a^bu'vdx,或\int_a^budv=uv|_a^b-\int_a^bvdu"><span></span><span></span></span>
解题方法
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)被积函数P_n(x)e^{\alpha x},\ P_n(x)sin{\alpha x},\ P_n(x)cos{\alpha x}:每次均取e^{\alpha x},sin\alpha x,cos\alpha x为v'(x),而多项式部分为u(x)"><span></span><span></span></span>;<br><span class="equation-text" data-index="1" data-equation="(2)被积函数P_n(x)lnx,\ P_n(x)arcsin{x},\ P_n(x)arctan{x}:每次均取lnx,arcsinx,arctanx等为u(x)" contenteditable="false"><span></span><span></span></span>;<br><span class="equation-text" data-index="2" data-equation="(3)被积函数e^{\alpha x}sin\beta x,e^{\alpha x}cos\beta x:每次均取e^{\alpha x}=v'(x)(或u(x)),而sin\beta x,cos\beta x为u(x)(或v'(x)),进行两次分部积分" contenteditable="false"><span></span><span></span></span>
几种特殊类型函数的积分法
有理函数的积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)\int\frac{A}{x-a}dx=Aln|x-a|+C"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="(2)\int\frac{A}{(x-a)^m}dx=-\frac{A}{m-1}·\frac{1}{(x-a)^{m-1}}+C(m\not=1)"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="(3)\int\frac{Ax+B}{x^2+px+q}dx=\frac{A}{2}·\int\frac{d(x^2+px+q)}{x^2+px+q}+(B-\frac{Ap}{2})\int \frac{d(x+\frac{p}{2})}{(x+\frac{p}{2})^2+(\sqrt{q-\frac{p^2}{4}})^2}=\frac{A}{2}·ln|{x^2+px+q}|+\frac{2B-Ap}{\sqrt{4q-p^2}}arctan\frac{2x+p}{\sqrt{4q-p^2}}+C" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="3" data-equation="(4)\int\frac{Ax+B}{(x^2+px+q)^m}dx=\frac{A}{2}·\int\frac{d(x^2+px+q)}{(x^2+px+q)^m}+(B-\frac{Ap}{2})\int \frac{d(x+\frac{p}{2})}{[(x+\frac{p}{2})^2+(\sqrt{q-\frac{p^2}{4}})^2]^m}=-\frac{A}{2(m-1)}·\frac{1}{(x^2+px+q)^{m-1}}+(B-\frac{Ap}{2})\int\frac{dx}{(x^2+px+q)^m}" contenteditable="false"><span></span><span></span></span><br>
当分式不容易直接进行分解时,可使用待定系数法:<br>设有真分式R(x)=P(x)/Q(x),Q(x)已被因式分解。<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="若分母中有一个因子(x-a)^n,则分解式有对应项\frac{A_1}{x-a}+\frac{A_2}{(x-a)^2}+...+\frac{A_n}{(x-a)^n}"><span></span><span></span></span>;<br><span class="equation-text" contenteditable="false" data-index="1" data-equation="若分母中有一个因子(x^2+px+q)^n(p^2-4q<0),则分解式有对应项\frac{A_1x+B_1}{x^2+px+q}+...+\frac{A_nx+B_n}{(x^2+px+q)^n}"><span></span><span></span></span>
简单无理函数的积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(1)\sqrt[n]{ax+b}:通过变量替换法,令t=\sqrt[n]{ax+b},则x=\phi(t)=\frac{1}{a}(t^n-b);"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(2)\sqrt[n]{\frac{ax+b}{cx+h}}:通过变量替换法,令t=\sqrt[n]{\frac{ax+b}{cx+h}},则x=\phi(t)=\frac{b-ht^n}{ct^n-a};" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="(3)\sqrt{ax^2+bx+c}:经过配方,可化为在第二换元积分法中所介绍的\sqrt{a^2-x^2}、\sqrt{a^2+x^2},\sqrt{x^2-a^2}。"><span></span><span></span></span>
三角函数有理式的积分
以sinx和cosx为变量的有理函数,通常记为R(sinx, cosx),<br>万能代换:<span class="equation-text" data-index="0" data-equation="tan\frac{x}{2}=t" contenteditable="false"><span></span><span></span></span>,使之有理化,有:<br><span class="equation-text" contenteditable="false" data-index="1" data-equation="sinx=2sin\frac{x}{2}cos\frac{x}{2}=\frac{2tan\frac{x}{2}}{sec^2\frac{x}{2}}=\frac{2t}{1+t^2},dx=\frac{2dt}{1+t^2}"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="cosx=cos^2\frac{x}{2}-sin^2\frac{x}{2}=\frac{1-tan^2\frac{x}{2}}{sec^2\frac{x}{2}}=\frac{1-t^2}{1+t^2}" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="3" data-equation="于是\int R(sinx,cosx)dx=\int R(\frac{2t}{1+t^2},\frac{1-t^2}{1+t^2})\frac{2dt}{1+t^2}"><span></span><span></span></span>
计算技巧
1. 利用定积分的几何意义直接得出某些积分的值;<br>2. 利用积分区间上奇偶函数的性质;<br>3. 利用周期函数的积分性质;<br>4. 利用积分公式:<br><span class="equation-text" data-index="0" data-equation="\int_0^{\frac{\pi}2}sin^nxdx=\int_0^{\frac{\pi}2}cos^nxdx=\begin{cases}\frac{n-1}{n}·\frac{n-3}{n-2}·\frac{n-5}{n-4}·...·\frac{2}{3},n≥3为奇数\\\frac{n-1}{n}·\frac{n-3}{n-2}·\frac{n-5}{n-4}·...·\frac{1}{2}·\frac{\pi}{2},n≥2为偶数\end{cases}" contenteditable="false"><span></span><span></span></span><br>5. 利用被积函数的分解与结合<br>(5.1)分解即分项积分法;<br>(5.2)对<span class="equation-text" contenteditable="false" data-index="1" data-equation="I=\int_a^bf(x)dx"><span></span><span></span></span>进行变量替换化成另一种形式<span class="equation-text" data-index="2" data-equation="I=\int_a^bg(x)dx" contenteditable="false"><span></span><span></span></span>,<br>将二者结合在一起更易算出结果<span class="equation-text" data-index="3" data-equation="2I=\int_a^b[f(x)+g(x)]dx" contenteditable="false"><span></span><span></span></span><br>
多元函数积分学
定义与性质
分类
二重积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="I=\iint\limits_{D}f(x,y)dσ=\lim\limits_{d\to0}\sum\limits_{i=1}^nf(ξ_i,η_i)Δσ_i"><span></span><span></span></span>
三重积分
<span class="equation-text" data-index="0" data-equation="J=\iiint\limits_{Ω}f(x,y,z)dV=\lim\limits_{d\to0}\sum\limits_{i=1}^nf(ξ_i,η_i,ζ_i)ΔV_i" contenteditable="false"><span></span><span></span></span>
第一类曲线积分
<span class="equation-text" data-index="0" data-equation="\int\limits_{L}f(x,y)ds=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^nf(ξ_i,η_i)Δs_i" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="\int\limits_{L}f(x,y,z)ds=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^nf(ξ_i,η_i,\zeta_i)Δs_i" contenteditable="false"><span></span><span></span></span><br>
第二类曲线积分
<span class="equation-text" data-index="0" data-equation="\iint\limits_{\Sigma}\overset{\rightharpoonup}{F}·d\overset{\rightharpoonup}{s}=\int\limits_{L}P(x,y)dx+Q(x,y)dy=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^n[P(ξ_i,η_i)Δx_i+Q(ξ_i,η_i)Δy_i]" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="\iint\limits_{\Sigma}\overset{\rightharpoonup}{F}·d\overset{\rightharpoonup}{s}=\int\limits_{L}P(x,y,z)dx+Q(x,y,z)dy+Q(x,y,z)dz" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^n[P(ξ_i,η_i,\zeta_i)Δx_i+Q(ξ_i,η_i,\zeta_i)Δy_i+R(ξ_i,η_i,\zeta_i)Δz_i]"><span></span><span></span></span>
第一类曲面积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{\Sigma}f(x,y,z)dS=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^nf(\xi_i,\eta_i,\zeta_i)\Delta S_i"><span></span><span></span></span>
第二类曲面积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{\Sigma}\overset{\rightharpoonup}{F}·d\overset{\rightharpoonup}{S}=\iint\limits_{\Sigma}P(x,y,z)dydz+Q(x,y,z)dzdx+R(x,y,z)dxdy"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^n[P(\xi_i,\eta_i,\eta_i)(\Delta S_i)_{yz}+P(\xi_i,\eta_i,\eta_i)(\Delta S_i)_{zx}+P(\xi_i,\eta_i,\eta_i)(\Delta S_i)_{xy}]"><span></span><span></span></span>
性质与若干基本结论
1. 线性性质:<span style="font-weight: normal;">函数的线性组合的积分=对应积分的线性组合</span><br>2. 对积分区域的可加性质;<br>3. 比较定理:<span style="font-weight: normal;">f(x,y)≤g(x,y)则f(x,y)的积分小于g(x,y)的积分;函数值有界[m,M]则积分有界[mA,MA](A为积分区域的面积);积分的绝对值≤函数绝对值的积分;</span><br>4. 积分中值定理:<br><span class="equation-text" data-index="0" data-equation="若f(x,y)在有界闭区域D上连续,则D上至少存在一点(ξ,η)使得\iint\limits_Df(x,y)dσ=f(ξ,η)A" contenteditable="false"><span></span><span></span></span><br>5. 连续非负函数积分性质:<span style="font-weight: normal;">积分区域D的任意子集D0内的积分值≤D内的积分值;若f(x,y)在D内连续和非负,且积分值为0,则函数值恒为0</span><br>6. 积分区域任意子区域积分为0则函数恒为0:
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\int_LPdx=0(L在垂直于x轴的平面上,即函数的x坐标恒为常数);"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="\int_LQdy=0(L在垂直于y轴的平面上,即函数的y坐标恒为常数);" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="\int_LRdz=0(L在垂直于z轴的平面上,即函数的z坐标恒为常数);" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="3" data-equation="\int_SPdydz=0(S垂直于Oyz平面,即S的法向量与Oyz平面平行);" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="4" data-equation="\int_SQdzdx=0(S垂直于Ozx平面,即S的法向量与Ozx平面平行);" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="5" data-equation="\int_SPdxdy=0(S垂直于Oxy平面,即S的法向量与Oxy平面平行);" contenteditable="false"><span></span><span></span></span><br>
积分之间的关系与比较
两类曲线积分的关系
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\int_{L_{\overset{\frown}{AB}}}Pdx+Qdy=\int_{L_{\overset{\frown}{AB}}}\overset{\rightharpoonup}{F}·\overset{\rightharpoonup}{τ}ds=\int_{L_{\overset{\frown}{AB}}}(Pcosα+Qcosβ)ds"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="\int_{L_{\overset{\frown}{AB}}}Pdx+Qdy+Rdz=\int_{L_{\overset{\frown}{AB}}}\overset{\rightharpoonup}{F}·\overset{\rightharpoonup}{τ}ds=\int_{L_{\overset{\frown}{AB}}}(Pcosα+Qcosβ+Rcosγ)ds"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="\overset{\rightharpoonup}{τ}"><span></span><span></span></span>为曲线弧沿从A到B方向的切线的方向余弦,或单位切向量
<div><span style="font-size: inherit;">两类曲面积分的关系</span><br></div>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{Σ}Pdydz+Qdzdx+Rdxdy=\iint\limits_{Σ}\overset{\rightharpoonup}{F}·d\overset{\rightharpoonup}{S}=\iint\limits_{Σ}\overset{\rightharpoonup}{F}·\overset{\rightharpoonup}{n}dS=\int_{L_{\overset{\frown}{AB}}}(Pcosα+Qcosβ+Rcosγ)dS"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="\overset{\rightharpoonup}{n}"><span></span><span></span></span>为任意点处法向量的方向余弦
第一类曲线(面)积分的比较
1. 第一类曲线(面)积分与曲线(面)的定向无关,第二类曲线(面)积分与曲线(面)的定向有关。<br><span class="equation-text" data-index="0" data-equation="若L^+与L^-是平面上同一条分段光滑曲线,但定向不同则积分互为相反数;" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="若S^+与S^-是同一块分块光滑曲面,但定向不同,则积分互为相反数;" contenteditable="false"><span></span><span></span></span><br>
重要公式
有关基本概念
1. 平面单连通区域D<span style="font-weight: normal;">(不含“洞”的区域)</span>:<span style="font-weight: normal;">设D为平面区域,<br>若D内任一闭曲线所围部分都属于D,否则称为</span>复连通区域<span style="font-weight: normal;">(含有“洞”的区域);</span><br>2. D为平面区域,L是D的边界,我们规定L的正向如下:当观察者沿这个方向行进时,D内在他近处的部分总在他的左边;<br>3. D是复连通区域,外边界闭曲线C,内边界闭曲线又C1,C2,...,Cn,则C的正向是逆时针方向,C1,C2,...,Cn的正向是顺时针方向。<br>4. 向量场<span class="equation-text" contenteditable="false" data-index="0" data-equation="F(x,y,z)=P(x,y,z)\overset{\rightharpoonup}{i}+Q(x,y,z)\overset{\rightharpoonup}{j}+R(x,y,z)\overset{\rightharpoonup}{k}"><span></span><span></span></span>
格林公式
1. 格林公式建立了平面上曲线积分与二重积分的联系:<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{D}(\frac{\partial Q}{\partial x}-\frac{\partial P}{\partial y})dxdy=\oint_LPdx+Qdy"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="\iint\limits_{D}(\frac{\partial Q}{\partial x}+\frac{\partial P}{\partial y})dxdy=\oint_LPdy-Qdx"><span></span><span></span></span>
高斯公式
2. 高斯公式建立了曲面积分与三重积分之间的联系:<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="\iiint\limits_{\Omega}(\frac{\partial P}{\partial x}+\frac{\partial Q}{\partial y}+\frac{\partial R}{\partial z})dV=\iint\limits_{S}Pdydz+Qdzdx+Rdxdy=\iint\limits_{S}(Pcos\alpha+Qcos\beta+Rcos\gamma)dS"><span></span><span></span></span>
物理意义
1. 向量场的通量:<span class="equation-text" data-index="0" data-equation="\iint\limits_{S}\overset{\rightharpoonup}{F}·\overset{\rightharpoonup}{n}dS=\iint\limits_{S}(Pcos\alpha+Qcos\beta+Rcos\gamma)dS=\iint\limits_{S}Pdydz+Qdzdx+Rdxdy=\iint\limits_{S}\overset{\rightharpoonup}{F}·d\overset{\rightharpoonup}{S}" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="n是S上任意点处的单位法向量\overset{\rightharpoonup}{n}=(cos\alpha,cos\beta,cos\gamma)" contenteditable="false"><span></span><span></span></span><br>2. 向量场的散度:<span class="equation-text" data-index="2" data-equation="divF=\frac{\partial P}{\partial x}+\frac{\partial Q}{\partial y}+\frac{\partial R}{\partial z}\overset{\Delta}=\nabla·F,其中\nabla=(\frac{\partial}{\partial x},\frac{\partial}{\partial y},\frac{\partial}{\partial z})为梯度算符" contenteditable="false"><span></span><span></span></span><br>3. 通量和散度的关系:<span class="equation-text" contenteditable="false" data-index="3" data-equation="\iiint\limits_{\Omega}div\overset{\rightharpoonup}{F}dV=\iint\limits_{S}\overset{\rightharpoonup}{F}·\overset{\rightharpoonup}{n}dS"><span></span><span></span></span>
斯托克斯公式
3. 斯托克斯公式建立了空间曲线积分与曲面积分之间的联系:<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{S}(\frac{\partial R}{\partial y}-\frac{\partial Q}{\partial z})dydz+(\frac{\partial P}{\partial z}-\frac{\partial R}{\partial x})dzdx+(\frac{\partial Q}{\partial x}-\frac{\partial P}{\partial y})dxdy"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="=\iint\limits_{S}[(\frac{\partial R}{\partial y}-\frac{\partial Q}{\partial z})cos\alpha+(\frac{\partial P}{\partial z}-\frac{\partial R}{\partial x})cos\beta+(\frac{\partial Q}{\partial x}-\frac{\partial P}{\partial y})cos\gamma]dS" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="=\iint\limits_{S}\begin{vmatrix}dydz&dzdx&dxdy\\\frac{\partial}{\partial x}&\frac{\partial}{\partial y}&\frac{\partial}{\partial z}\\P&Q&R\end{vmatrix}=\iint\limits_{S}\begin{vmatrix}cos\alpha&cos\beta&cos\gamma\\\frac{\partial}{\partial x}&\frac{\partial}{\partial y}&\frac{\partial}{\partial z}\\P&Q&R\end{vmatrix}dS"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="3" data-equation="=\int_\Gamma Pdx+Qdy+Rdz"><span></span><span></span></span>
物理意义
1. 向量场的环流量:<span class="equation-text" data-index="0" data-equation="\oint_\Gamma\overset{\rightharpoonup}{F}·\overset{\rightharpoonup}{\tau}ds=\oint_\Gamma(Pcos\alpha+Qcos\beta+Rcos\gamma)ds=\oint_\Gamma Pdx+Qdy+Rdz=\oint_\Gamma \overset{\rightharpoonup}{F}·d\overset{\rightharpoonup}{s}" contenteditable="false"><span></span><span></span></span><br><br><span class="equation-text" data-index="1" data-equation="\tau是\Gamma上任意点(x,y,z)处单位切向量\overset{\rightharpoonup}{\tau}=(cos\alpha,cos\beta,cos\gamma)" contenteditable="false"><span></span><span></span></span><br>2. 旋度及其计算公式:<span class="equation-text" data-index="2" data-equation="rot\overset{\rightharpoonup}{F}=(\frac{\partial R}{\partial y}-\frac{\partial Q}{\partial z},\frac{\partial P}{\partial z}-\frac{\partial R}{\partial x},\frac{\partial Q}{\partial x}-\frac{\partial P}{\partial y})\overset{\Delta}=\begin{vmatrix}\overset{\rightharpoonup}{i}&\overset{\rightharpoonup}{j}&\overset{\rightharpoonup}{k}\\\frac{\partial}{\partial x}&\frac{\partial}{\partial y}&\frac{\partial}{\partial z}\\P&Q&R\end{vmatrix}\overset{\Delta}{=}\nabla×\overset{\rightharpoonup}{F}" contenteditable="false"><span></span><span></span></span><br>3. 环流量与旋度的关系:<span class="equation-text" contenteditable="false" data-index="3" data-equation="\iint\limits_Srot\overset{\rightharpoonup}{F}·\overset{\rightharpoonup}{n}dS=\int_\Gamma\overset{\rightharpoonup}{F}·\overset{\rightharpoonup}{τ}ds"><span></span><span></span></span>
积分计算
转换积分类型
曲线积分化为定积分
第一类曲线积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\int_Lf(x,y)ds=\int_α^βf(φ(t),ψ(t))\sqrt{φ'^2(t)+ψ'^2(t)}dt=\int_a^bf(x,y(x))\sqrt{1+y'^2_x}dx=\int_α^βf(rcosθ,rsinθ)\sqrt{r^2(θ)+r'^2(θ)}dθ"><span></span><span></span></span>
第二类曲线积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\int_{L_{\overset{\frown}{AB}}}P(x,y)dx+Q(x,y)dy=\int_α^β[P(φ(t),ψ(t))φ'(t)+Q(φ(t),ψ(t))ψ'(t)]dt=\int_a^b[P(x,y(x))+Q(x,y(x))y'(x)]dx"><span></span><span></span></span>
二重积分化为累次积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{D}f(x,y)dσ=\int^b_adx\int^{φ_2(x)}_{φ_1(x)}f(x,y)dy=\int^β_αdy\int^{ψ_2(x)}_{ψ_1(x)}f(x,y)dx"><span></span><span></span></span>
三重积分化为累次积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iiint\limits_{Ω}dV=\iint\limits_Ddxdy\int^{z_2(x,y)}_{z_1(x,y)}f(x,y,z)dz=\int^{β}_{α}dz\iint\limits_{D(z)}f(x,y,z)dxdy"><span></span><span></span></span>
曲面积分化为二重积分
1. 第一类曲面积分<br>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{Σ}f(x,y,z)dS=\iint\limits_{Σ}f(x,y,z(x,y))\sqrt{1+z'^2_x+z'^2_y}dσ"><span></span><span></span></span>
2. 第二类曲面积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{Σ}Pdydz+Qdzdx+Rdxdy=±\iint\limits_{D_{xy}}[P(x,y,z(x,y))(\frac{-\partial z}{\partial x})+Q(x,y,z(x,y))(\frac{-\partial z}{\partial y})+R(x,y,z(x,y))]dxdy"><span></span><span></span></span>
转换积分坐标系
平移变换
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{D}f(x,y)dxdy=\iint\limits_{D'}f(u+a,v+b)dudv"><span></span><span></span></span>
二重积分的极坐标变换
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iint\limits_{D}f(x,y)dσ=\iint\limits_{D'}f(rcosθ,rsinθ)rdrdθ"><span></span><span></span></span>
三重积分的柱坐标变换
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iiint\limits_{Ω}f(x,y,z)dV=\iiint\limits_{Ω'}f(rcosθ,rsinθ,z)rdrdθdz"><span></span><span></span></span>
三重积分的球坐标变换
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\iiint\limits_Ωf(x,y,z)dV=\iiint\limits_{Ω'}f(ρsinφcosθ,ρsinφsinθ,ρcosφ)ρ^2sinφdρdθdφ"><span></span><span></span></span>
简化积分
1. 选择积分顺序<br>2. 利用区域的对称性与被积函数的奇偶性<br>3. 某些情形下要利用分块积分法<br>4. 选择变量替换<br>5. 计算曲线、曲面积分时,注意利用曲线或曲面方程化简被积函数<br>6. 利用多元函数积分的几何意义或物理意义<br>7. 计算第二类曲面积分选择投影方向<br>8. 利用各类积分之间相互转化来简化积分计算
微积分的应用
微分学的应用
基础应用
泰勒公式的应用
带皮亚诺余项的泰勒公式的若干应用
1. 利用泰勒公式求未定式的极限<br>2. 利用泰勒公式确定无穷小的阶<br>3. 由泰勒公式的系数求函数在指定点x=x0处高阶导数的值<span class="equation-text" contenteditable="false" data-index="0" data-equation="f^{(n)}(x_0)"><span></span><span></span></span>
带拉格朗日余项的泰勒公式的若干应用
1. 利用泰勒公式证明不等式<br> 1.1 通过估计泰勒公式余项的大小来证明不等式<br> 1.2 由函数与二阶导数估计一阶导数证明不等式<br>2. 利用泰勒公式证明函数或高阶导数存在满足某些要求的特征点
微分中值定理的应用
1. 证明不等式的方法<br>2. 证明函数或导数存在零点或其他某些特征点的方法及确定零点个数的方法<br>3. 求极限的洛必达法则<br>4. 函数的最值问题及应用问题
复合函数求导法的应用
1. 幂指数函数、反函数、由参数方程确定的函数、隐函数微分法<br>2. 隐函数微分法<br>3. 变量替换下的方程简化;<br>4. 多元函数问题转化为一元函数;
几何应用
平面曲线<span style="font-weight: normal;">的</span>切线<span style="font-weight: normal;">与</span>法线
<span style="font-weight: normal;">(1)用</span>显式方程<span style="font-weight: normal;">表示的平面曲线:【</span>切线、法线】:<span class="equation-text" data-index="0" data-equation="y=y_0+f'(x_0)(x-x_0),\begin{cases}y=y_0+\frac{-1}{f'(x_0)}(x-x_0),(f'(x_0)≠0)\\x=x_0,(f'(x_0)=0)\end{cases}" contenteditable="false"><span></span><span></span></span><br><span style="font-weight: normal;">(2)用</span>参数方程<span style="font-weight: normal;">表示的平面曲线</span>:<span style="font-weight: normal;">【</span>切线、法线】:<span class="equation-text" data-index="1" data-equation="\frac{x-x_0}{x'(t_0)}=\frac{y-y_0}{y'(t_0)},\frac{x-x_0}{-y'(t_0)}=\frac{y-y_0}{x'(t_0)}" contenteditable="false"><span></span><span></span></span><br><span style="font-weight: normal;">(3)用 </span>极坐标 <span style="font-weight: normal;">表示的平面曲线</span>:【切线、法线】:根据<span style="font-weight: normal;"></span><span class="equation-text" data-index="2" data-equation="r=r(\theta),即x=r(\theta)cos\theta,y=r(\theta)sin\theta" contenteditable="false"><span></span><span></span></span>先求导数<br><span style="font-weight: normal;">(4)用</span>隐式方程<span style="font-weight: normal;">表示的平面曲线:【</span>切线、法线】:<span class="equation-text" data-index="3" data-equation="\frac{\partial f(x_0,y_0)}{\partial x}(x-x_0)+\frac{\partial f(x_0,y_0)}{\partial y}(y-y_0)=0,\frac{x-x_0}{\frac{\partial f(x_0,y_0)}{\partial x}}=\frac{y-y_0}{\frac{\partial f(x_0,y_0)}{\partial y}}" contenteditable="false"><span></span><span></span></span><br><span style="font-weight: normal;"></span>
平面曲线<span style="font-weight: normal;">的</span>曲率
<span style="font-weight: normal;">(1)曲率是点的切线的倾角对弧长导数的绝对值</span><span class="equation-text" data-index="0" data-equation="K=|\frac{d\alpha}{ds}|" contenteditable="false"><span></span><span></span></span>
空间曲线<span style="font-weight: normal;">的</span>切线<span style="font-weight: normal;">与</span>法平面
用参数方程表示的空间曲线:<br><span style="font-weight: normal;">x=x(t), y=y(t), z=z(t),导数不全为0</span><br>
(1)切线方程:<span class="equation-text" data-index="0" data-equation="\frac{x-x_0}{x'(t_0)}=\frac{y-y_0}{y'(t_0)}=\frac{z-z_0}{z'(t_0)}" contenteditable="false"><span></span><span></span></span><br>(2)法平面方程:<span class="equation-text" data-index="1" data-equation="x'(t_0)(x-x_0)+y'(t_0)(y-y_0)+z'(t_0)(z-z_0)=0" contenteditable="false"><span></span><span></span></span>
作为两曲面交线的空间曲线:<br><span style="font-weight: normal;">F(x, y, z)=0, G(x, y, z)=0</span>
<span style="font-weight: normal;"></span>(1)切线方程:<span class="equation-text" data-index="0" data-equation="\begin{cases}\frac{\partial F(M_0)}{\partial x}(x-x_0)+\frac{\partial F(M_0)}{\partial y}(y-y_0)+\frac{\partial F(M_0)}{\partial z}(z-z_0)=0\\\frac{\partial G(M_0)}{\partial x}(x-x_0)+\frac{\partial G(M_0)}{\partial y}(y-y_0)+\frac{\partial G(M_0)}{\partial z}(z-z_0)=0\end{cases}" contenteditable="false"><span></span><span></span></span>,两个曲面的切平面的交线<br> 或:<span class="equation-text" data-index="1" data-equation="\frac{x-x_0}{\frac{\partial (F,G)}{\partial (y,z)}|_{M_0}}=\frac{y-y_0}{\frac{\partial (F,G)}{\partial (z,x)}|_{M_0}}=\frac{z-z_0}{\frac{\partial (F,G)}{\partial (x,y)}|_{M_0}}" contenteditable="false"><span></span><span></span></span>,其中<span class="equation-text" data-index="2" data-equation="\frac{\partial (F,G)}{\partial (u,v)}=\begin{vmatrix}\frac{\partial F}{\partial u}&\frac{\partial F}{\partial v}\\\frac{\partial G}{\partial u}&\frac{\partial G}{\partial v}\end{vmatrix}" contenteditable="false"><span></span><span></span></span><br>(2)法平面方程:<span class="equation-text" data-index="3" data-equation="\frac{\partial (F,G)}{\partial (y,z)}|_{M_0}(x-x_0)+\frac{\partial (F,G)}{\partial (z,x)}|_{M_0}(y-y_0)+\frac{\partial (F,G)}{\partial (x,y)}|_{M_0}(z-z_0)=0" contenteditable="false"><span></span><span></span></span><br>(3)空间曲线在M0点处的切向量:<br><span class="equation-text" data-index="4" data-equation="gradF(M_0)×gradG(M_0)=\begin{vmatrix}\overset{\rightharpoonup}{i}&\overset{\rightharpoonup}{j}&\overset{\rightharpoonup}{k}\\\frac{\partial F(M_0)}{x}&\frac{\partial F(M_0)}{y}&\frac{\partial F(M_0)}{z}\\\frac{\partial G(M_0)}{x}&\frac{\partial G(M_0)}{y}&\frac{\partial G(M_0)}{z}\end{vmatrix}=(\frac{\partial (F,G)}{\partial (y,z)}|_{M_0},\frac{\partial (F,G)}{\partial (z,x)}|_{M_0},\frac{\partial (F,G)}{\partial (x,y)}|_{M_0})" contenteditable="false"><span></span><span></span></span>
空间曲面<span style="font-weight: normal;">的</span>切平面<span style="font-weight: normal;">与</span>法线
用隐式方程表示的曲面:<br><span style="font-weight: normal;">F(x, y, z)=0的偏导不全为0</span><br>
(1)切平面方程:<span class="equation-text" data-index="0" data-equation="\frac{\partial F(M_0)}{\partial x}(x-x_0)+\frac{\partial F(M_0)}{\partial y}(y-y_0)+\frac{\partial F(M_0)}{\partial z}(z-z_0)=0" contenteditable="false"><span></span><span></span></span><br>(2)法线方程:<span class="equation-text" data-index="1" data-equation="\frac{x-x_0}{\frac{\partial F(M_0)}{\partial x}}=\frac{y-y_0}{\frac{\partial F(M_0)}{\partial y}}=\frac{z-z_0}{\frac{\partial F(M_0)}{\partial z}}" contenteditable="false"><span></span><span></span></span><br>(3)空间曲线在M0点处的法向量:<span class="equation-text" data-index="2" data-equation="gradF(M_0)=(\frac{\partial F(M_0)}{\partial x},\frac{\partial F(M_0)}{\partial y},\frac{\partial F(M_0)}{\partial z})" contenteditable="false"><span></span><span></span></span>
用显式方程表示的曲面:<br><span style="font-weight: normal;">z=f(x, y)</span>
(1)切平面方程:<span class="equation-text" data-index="0" data-equation="f'_x(x_0,y_0)(x-x_0)+f'_y(x_0,y_0)(y-y_0)-(z-z_0)=0" contenteditable="false"><span></span><span></span></span><br>(2)法线方程:<span class="equation-text" data-index="1" data-equation="\frac{x-x_0}{f'_x(x_0,y_0)}=\frac{y-y_0}{f'_y(x_0,y_0)}=\frac{z-z_0}{-1}" contenteditable="false"><span></span><span></span></span><br>(3)空间曲线在M0点处的法向量:<span class="equation-text" data-index="2" data-equation="±(-f'_x(x_0,y_0),-f'_y(x_0,y_0),1)" contenteditable="false"><span></span><span></span></span>
物理应用
用导数描述某些物理量
<span style="font-weight: normal;">(1)速度时位移的导数;<br>(2)线密度是线质量的导数;<br>(3)电流强度是电荷量关于时间的导数;<br>(4)比热是热量的导数;<br>(5)功率是功的导数;</span>
积分学应用
几何应用
平面图形的面积<br>
<br><span class="equation-text" data-index="0" data-equation="直角坐标系:S=\int_a^b|f(x)-g(x)|dx=\int_{\alpha}^{\beta}|φ(y)-\psi(y)|dy;" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="极坐标系:S=\frac12\int_{\alpha}^{\beta}[r_2^2(\theta)-r_2^1(\theta)]=\int_a^b[\theta_2(r)-\theta_1(r)]rdr" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="参数方程下:S=\int_a^bydx=\int_\alpha^\beta\psi(t)dφ(t)=\int_\alpha^\beta\psi(t)φ'(t)dt" contenteditable="false"><span></span><span></span></span>
平面曲线的弧微分与弧长
<br><span class="equation-text" data-index="0" data-equation="s=\int_a^b\sqrt{1+f'^2(x)}dx=\int_\alpha^\beta\sqrt{x'^2(t)+y'^2(t)}dt=\int_\alpha^\beta\sqrt{r'^2(\theta)+r'^2(\theta)}d\theta" contenteditable="false"><span></span><span></span></span>
平面曲面的曲率:曲率、曲率半径、曲率圆
<br><span class="equation-text" data-index="0" data-equation="K=|\frac{d\alpha}{ds}|=\frac{|x'(t)y''(t)-x''(t)y'(t)|}{[x'^2(t)+y'^2(t)]^{\frac32}}=\frac{|y''|}{(1+y'^2)^{\frac32}}" contenteditable="false"><span></span><span></span></span>
空间图形的体积
(4.1)平行截面面积为已知的立体的体积:<span class="equation-text" data-index="0" data-equation="V=\int_\alpha^\beta S(z)dz" contenteditable="false"><span></span><span></span></span><br>(4.2)旋转体的体积:<span class="equation-text" data-index="1" data-equation="V_x=\pi\int_a^bf^2(x)dx;V_y=2\pi\int_a^bx|f(x)|dx" contenteditable="false"><span></span><span></span></span><br>(4.3)柱形长条区域的体积:<span class="equation-text" contenteditable="false" data-index="2" data-equation="V=\iiint\limits_{\Omega}dV=\iint\limits_{D}(\int_{z_1(x,y)}^{z_2(x,y)}dz)dxdy=\iint\limits_{D}[z_2(x,y)-z_1(x,y)]dxdy"><span></span><span></span></span>
曲面面积
(5.1)旋转面的(侧)面积<br><span class="equation-text" data-index="0" data-equation="(1)圆台的侧面积:S=2\pi l\frac{y_A+y_B}{2}" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="1" data-equation="(2)直角坐标系下:S=2\pi \int_a^bf(x)\sqrt{1+f'^2(x)}dx" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="2" data-equation="(3)参数方程下:S=2\pi \int_\alpha^\beta y(t)\sqrt{x'^2(t)+y'^2(t)}dt" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="3" data-equation="(4)极坐标下:S=2\pi \int_\alpha^\beta r(\theta)sin\theta\sqrt{r^2(\theta)+r'^2(\theta)}d\theta" contenteditable="false"><span></span><span></span></span><br>(5.2)一般曲面的面积<br><span class="equation-text" contenteditable="false" data-index="4" data-equation="(1)A=\iint\limits_{D}\frac{d\sigma}{|cos\gamma|}=\iint\limits_{D}\sqrt{1+f_x^2+f_y^2}dxdy"><span></span><span></span></span>
物理应用
函数在区间上的平均值
<br><span class="equation-text" data-index="0" data-equation="\bar y=\frac{1}{b-a}\int_a^bf(x)dx" contenteditable="false"><span></span><span></span></span>
液体的静压力
<span class="equation-text" data-index="0" data-equation="P=\int_a^b\gamma xf(x)dx" contenteditable="false"><span></span><span></span></span><br>
变力做功
(1)变力F(x):<span class="equation-text" data-index="0" data-equation="W=\int_a^bF(x)dx" contenteditable="false"><span></span><span></span></span><br>(2)变力F(x, y)=(P(x, y), Q(x, y)):<span class="equation-text" data-index="1" data-equation="W=\int_{A}^{B}Pdx+Qdy" contenteditable="false"><span></span><span></span></span><br>(3)变力F(x, y, z)=(P(x, y, z), Q(x, y, z), R(x, y, z)):<span class="equation-text" contenteditable="false" data-index="2" data-equation="W=\int_{A}^BPdx+Qdy+Rdz"><span></span><span></span></span>
引力问题
(1)引力公式:<span class="equation-text" data-index="0" data-equation="F=k\frac{m_1m_2}{r^2}" contenteditable="false"><span></span><span></span></span>,<br>(2)令ρ(x,y,z)为空间曲线L的线密度,则曲线L对外点M0处质量为m0的质点的引力为<br><span class="equation-text" contenteditable="false" data-index="1" data-equation="\overset{\rightharpoonup}{F}=\int_Lkm_0\rho(x,y,z)\frac{1}{r^3}(x-x_0,y-y_0,z-z_0)ds"><span></span><span></span></span>
质量、质心、形心与转动惯量
(1)质量:<span class="equation-text" contenteditable="false" data-index="0" data-equation="M=\iiint\limits_{\Omega}\rho(x,y,z)dV"><span></span><span></span></span><br>(2)质心:<br>(2.1)三维空间物体的质心<br><span class="equation-text" contenteditable="false" data-index="1" data-equation="(\bar{x},\bar{y},\bar{z})=\frac{(\iiint\limits_{\Omega}x\rho(x,y,z)dV,\iiint\limits_{\Omega}y\rho(x,y,z)dV,\iiint\limits_{\Omega}z\rho(x,y,z)dV)}{\iiint\limits_{\Omega}\rho(x,y,z)dV},体密度\rho(x,y,z)为常数时,也是形心"><span></span><span></span></span><br>(2.2)均匀线密度为ρ的平面曲线的质心(形心)<br><span class="equation-text" data-index="2" data-equation="(\bar x,\bar y)=(\frac{M_y}{M},\frac{M_x}{M})=(\frac{\int_0^lx(s)ds}{l},\frac{\int_0^ly(s)ds}{l})=(\frac{\int_\alpha^\beta \phi(t)\sqrt{\phi'^2(t)+\psi'^2(t)}dt}{\int_\alpha^\beta \sqrt{\phi'^2(t)+\psi'^2(t)}dt},\frac{\int_\alpha^\beta \psi(t)\sqrt{\phi'^2(t)+\psi'^2(t)}dt}{\int_\alpha^\beta \sqrt{\phi'^2(t)+\psi'^2(t)}dt})" contenteditable="false"><span></span><span></span></span><br>(2.3)均匀密度平面图形的质心(形心)<br><span class="equation-text" data-index="3" data-equation="(\bar x,\bar y)=(\frac{M_y}{M},\frac{M_x}{M})=(\frac{\int_a^b x[f(x)-g(x)]dx}{\int_a^b [f(x)-g(x)]dx},\frac{\frac12\int_a^b x[f^2(x)-g^2(x)]dx}{\int_a^b [f(x)-g(x)]dx})" contenteditable="false"><span></span><span></span></span><br>(3)转动惯量:<span class="equation-text" contenteditable="false" data-index="4" data-equation="I_x=\iiint\limits_{\Omega}(y^2+z^2)\rho(x,y,z)dV,I_y=\iiint\limits_{\Omega}(x^2+z^2)\rho(x,y,z)dV"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="5" data-equation="I_z=\iiint\limits_{\Omega}(x^2+y^2)\rho(x,y,z)dV,I_o=\iiint\limits_{\Omega}(x^2+y^2+z^2)\rho(x,y,z)dV"><span></span><span></span></span>
流量
流速v(x, y, z)=(P(x, y, z), Q(x, y, z), R(x, y, z)),则流体流过定向曲面S的流量为<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="q=\iint\limits_{S}\overset{\rightharpoonup}{v}·\overset{\rightharpoonup}{n}=\iint\limits_{S}{Pcos\alpha+Qcos\beta+Rcos\gamma}dS=\iint\limits_{S}Pdydz+Qdzdx+Rdxdy"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="\overset{\rightharpoonup}{n}=(cos\alpha,cos\beta,cos\gamma)是曲面S的单位向量"><span></span><span></span></span>
基本方法——微元分析法
1. 分割、近似、求和、取极限<br><span class="equation-text" contenteditable="false" data-index="0" data-equation="F(b)-F(a)\overset{整体改变量化为局部改变量之和}=\sum\limits_{i=1}^n[F(x_i)-F(x_{i-1})]\overset{局部上用微分近似函数改变量}{≈}\sum\limits_{i=1}^nf(x_i)\Delta x_i"><span></span><span></span></span><br><span style="font-weight: normal;">取极限从近似转化为精确,即</span><span class="equation-text" contenteditable="false" data-index="1" data-equation="F(b)-F(a)=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^nf(x_i)\Delta x_i=\int_a^bf(x)dx"><span></span><span></span></span><br>2. 上述四步中关键的是分割和近似,从微分式和积分式的等价性来看:<br><span class="equation-text" contenteditable="false" data-index="2" data-equation="若f(x)在[a,b]上连续,则dF(x)=f(x)dx(\forall x\in [a,b])\leftrightarrows\int_a^xf(t)dt=F(x)-F(a)(\forall x\in [a,b])"><span></span><span></span></span><br>3. 四步归结为两步有:<br><span style="font-weight: normal;">(1)求出F(x)的微分式dF(x)=f(x)dx,其中f(x)是已知的,F(x)是要求的;</span><br><span style="font-weight: normal;">(2)将微分式积分,即</span><span class="equation-text" data-index="3" data-equation="F(b)-F(a)=\int_a^bf(x)dx" contenteditable="false"><span></span><span></span></span><br>4. 写出F(x)的微分式的方法——微元分析法:<br><span style="font-weight: normal;">(1)任取微元区间[x,x+Δx],求出ΔF(x)=F(x+Δx)-F(x)≈f(x)Δx,当Δx→0时近似式转化为等式,即dF(x)=f(x)dx。</span>
利用定积分求某些n项和式数列的极限
设f(x)在[a, b]连续,则f(x)在[a, b]可积,即f(x)在[a, b]上任意积分和均以<span class="equation-text" contenteditable="false" data-index="0" data-equation="\int_a^bf(x)dx"><span></span><span></span></span>为极限,<br>即<span class="equation-text" contenteditable="false" data-index="1" data-equation="\int_a^bf(x)dx=\lim\limits_{\lambda\to0}\sum\limits_{i=1}^nf(\xi_i)\Delta x_i,其中\lambda=\max\limits_{1≤i≤n}\{\Delta x_i\}"><span></span><span></span></span>,常见的情形如下:<br><span class="equation-text" contenteditable="false" data-index="2" data-equation="(1)\int_a^bf(x)dx=\lim\limits_{n\to\infin}\sum\limits_{i=1}^nf[a+\frac{i(b-a)}{n}]\frac{b-a}{n};"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="3" data-equation="(2)\int_a^bf(x)dx=\lim\limits_{n\to\infin}\sum\limits_{i=1}^nf[a+\frac{(i-1)(b-a)}{n}]\frac{b-a}{n};"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="4" data-equation="(3)\lim\limits_{n\to\infin}\sum\limits_{i=1}^na_i=\lim\limits_{n\to\infin}\sum\limits_{i=1}^n\frac{1}{n}f({\frac{i}{n}})=\int_0^1f(x)dx"><span></span><span></span></span>.
用格林公式、高斯公式、斯托克斯公式<br>简化多元函数积分的计算<br>
<span style="font-weight: normal;">应用格林公式计算曲线积分</span><br>
<span style="font-weight: normal;">(1.1)直接用格林公式计算第二类曲线积分或估计第二类曲线积分;</span><br><span style="font-weight: normal;">(1.2)用格林公式求非闭曲线的第二类曲线积分;</span><br><span style="font-weight: normal;">(1.3)用格林公式把难求的曲线积分转化为易求的曲线积分。</span>
<span style="font-weight: normal;">应用高斯公式计算曲线积分</span><br><span style="font-weight: normal;"></span><span style="font-weight: normal;"></span>
<span style="font-weight: normal;">(1.1)直接用高斯公式求曲面积分;</span><br><span style="font-weight: normal;">(1.2)用高斯公式求封闭曲面的积分;</span><br><span style="font-weight: normal;">(1.3)用高斯公式把难求的曲面积分转化为易求得曲面积分。</span>
应用斯托克斯公式计算曲线积分
向量代数和空间解析几何
向量代数
基本概念和表示法
空间直角坐标系、向量、矢量、向径、模、单位向量、零向量、共线向量、共面向量、方向角、方向余弦、方向数
向量的运算
加减、数乘向量、数量积(点积,内积)、向量积(叉积,外积)、混合积<span class="equation-text" contenteditable="false" data-index="0" data-equation="(a_1,a_2,a_3)=(a_1×a_2)·a_3"><span></span><span></span></span>
运算法则
1. 加法和数乘运算法则<br>2. 数量积符合交换律、结合律、分配律<br>3. 向量积和混合积可以从行列式的计算性质中推出
空间解析几何
平面与直线
求平面与直线的方程
平面:点法式、一般式、向量式、参数式<br>直线、一般式、参数式,对称式(标准式)
平面束方程
判断直线、平面的位置关系,计算夹角
直线的方向向量和平面的法向量的位置关系与夹角
点、平面、直线的距离
根据方向向量和构造向量求解
曲面与曲线
概念及表示法
球面、旋转曲面、柱面、二次曲面
柱面和旋转面方程的求法
取任一点(x0, y0),根据解析几何化简,然后取(x0, y0)为任意(x, y)即可
二次曲面的标准方程及其图形
椭球面、<br>旋转抛物面、椭圆抛物面、双曲抛物面、<br>单叶双曲面、双叶双曲面、<br>二次锥面、<br>抛物柱面、椭圆柱面、双曲柱面
空间曲线在坐标平面上投影的方程
投影点、投影曲线、投影柱面
常微分方程
基本概念
常微分方程、线性微分方程、非线性微分方程、微分方程的阶、微分方程的解、微分方程的通解和特解、微分方程的初始条件与初值问题
分类与解法
一阶微分方程
基本类型
一阶线性方程
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y'+p(x)y=q(x)"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y=e^{-\int{p(x)dx}}[C+\int{q(x)e^{\int{p(x)dx}}dx}]"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y'+p(x)y=0"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y=Ce^{-\int{p(x)dx}}"><span></span><span></span></span>
变量可分离的方程:<span class="equation-text" contenteditable="false" data-index="0" data-equation="y'=f(x)g(y)"><span></span><span></span></span>
全微分方程:<span class="equation-text" contenteditable="false" data-index="0" data-equation="P(x,y)dx+Q(x,y)dy=0,存在du=Pdx+Qdy"><span></span><span></span></span>
1. 特殊路径积分法:<br>2. 不定积分法<br>3. 凑微分法
可变量替换为<br>基本类型的几类
齐次方程:<span class="equation-text" contenteditable="false" data-index="0" data-equation="y'=f(\frac{y}{x})"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="u=\frac{y}{x}"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y'=f(ax+by+c)"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="u=ax+by+c"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y'=f(\frac{a_{1}x+b_{1}y+c_{1}}{a_{2}x+b_{2}y+c_{2}})"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(a_1,b_1)与(a_2,b_2)线性不相关:u=x-α,v=y-β,α,β为线性方程组的解"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="(a_1,b_1)与(a_2,b_2)线性相关:z=a_1x+b_1y"><span></span><span></span></span>
伯努利方程:<span class="equation-text" contenteditable="false" data-index="0" data-equation="y'+p(x)y=q(x)y^α"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="z=y^{1-α}"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\frac{dy}{dx}=\frac{h(y)}{p(y)x+q(y)}(或\frac{dy}{dx}=\frac{h(y)}{p(y)x+q(y)x^{α}})"><span></span><span></span></span>
自变量与因变量互换
高阶微分方程
二阶线性常系数方程
齐次:<span class="equation-text" contenteditable="false" data-index="0" data-equation="y''+py'+qy=0"><span></span><span></span></span>
1. 特征方程:<span class="equation-text" contenteditable="false" data-index="0" data-equation="λ^2+pλ+q=0,Δ=p^2-4q"><span></span><span></span></span><br> Δ>0有通解:<span class="equation-text" contenteditable="false" data-index="1" data-equation="y(x)=C_1e^{λ_1x}+C_2e^{λ_1x}"><span></span><span></span></span><br> Δ=0有通解:<span class="equation-text" data-index="2" data-equation="y(x)=(C_1+C_2x)e^{λ_1x}" contenteditable="false"><span></span><span></span></span><br> Δ<0有通解:<span class="equation-text" data-index="3" data-equation="y(x)=e^{αx}(C_1cosβx+C_2sinβx)" contenteditable="false"><span></span><span></span></span><br>
非齐次:<span class="equation-text" contenteditable="false" data-index="0" data-equation="y''+py'+qy=f(x)"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="f(x)=P_n(x)"><span></span><span></span></span>
0非根:<span class="equation-text" contenteditable="false" data-index="0" data-equation="y^*(x)=H_n(x)"><span></span><span></span></span><br>0单根:<span class="equation-text" data-index="1" data-equation="y^*(x)=xH_n(x)" contenteditable="false"><span></span><span></span></span><br>0重根:<span class="equation-text" data-index="2" data-equation="y^*(x)=x^2H_n(x)" contenteditable="false"><span></span><span></span></span><br>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="f(x)=P_n(x)e^{αx}"><span></span><span></span></span>
α非根:<span class="equation-text" contenteditable="false" data-index="0" data-equation="y^*(x)=H_n(x)e^{αx}"><span></span><span></span></span><br>α单根:<span class="equation-text" data-index="1" data-equation="y^*(x)=xH_n(x)e^{αx}" contenteditable="false"><span></span><span></span></span><br>α重根:<span class="equation-text" data-index="2" data-equation="y^*(x)=x^2H_n(x)e^{αx}" contenteditable="false"><span></span><span></span></span><br>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="f(x)=e^{αx}[P_n(x)sinβx+Q_m(x)cosβx]"><span></span><span></span></span>
α±iβ非根:<span class="equation-text" contenteditable="false" data-index="0" data-equation="y^*(x)=e^{αx}[R_l(x)cosβx+S_l(x)sinβx]"><span></span><span></span></span><br>α±iβ是根:<span class="equation-text" data-index="1" data-equation="y^*(x)=xe^{αx}[R_l(x)cosβx+S_l(x)sinβx]" contenteditable="false"><span></span><span></span></span><br>
n阶线性常系数方程
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y^{(n)}+p_1y^{(n-1)}+p_2y^{(n-2)}+...+p_ny=0"><span></span><span></span></span>
<span style="font-weight: normal;">1. 特征方程:</span><span class="equation-text" data-index="0" data-equation="λ^{n}+p_1λ^{n-1}+p_2λ^{n-2}+...+p_n=0" contenteditable="false"><span></span><span></span></span><span style="font-weight: normal;"><br>2. 特征方程不能求出全部的解,故只做以下三类情况讨论:</span><br> (1)<span style="font-weight: normal;">λ1, ..., λn是n个相异实根,则通解为:</span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="y(x)=C_1e^{λ_1x}+C_2e^{λ_2x}+...+C_ne^{λ_nx}"><span></span><span></span></span><br> (2)<span style="font-weight: normal;">λ0为特征方程的k重实根,则通解中含有:</span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="(C_1+C_2x+...+C_kx^{k-1})e^{λ_0x}"><span></span><span></span></span><br> (3)<span style="font-weight: normal;">α±iβ为特征方程的k重实根,则通解中含有:</span><br><span class="equation-text" contenteditable="false" data-index="3" data-equation="e^{αx}[(C_1+C_2x+...+C_kx^{k-1})cosβx+(D_1+D_2x+...+D_kx^{k-1})sinβx]"><span></span><span></span></span>
可降解的高阶方程
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y^{(n)}=f(x)"><span></span><span></span></span>
n次积分
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y''=f(x,y')"><span></span><span></span></span>
令<span class="equation-text" contenteditable="false" data-index="0" data-equation="p=y',则有p'=f(x,p)"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="y''=f(y,y')"><span></span><span></span></span>
令<span class="equation-text" contenteditable="false" data-index="0" data-equation="p=y',则有p\frac{dp}{dy}=f(y,p)[y''=\frac{d^2y}{dx^2}=\frac{dp}{px}=\frac{dp}{py}\frac{dy}{px}=p\frac{dp}{py}]"><span></span><span></span></span>
<span style="font-weight: normal;">欧拉方程——</span>特殊的二阶线性变系数方程
<span class="equation-text" contenteditable="false" data-index="0" data-equation="x^ny^{(n)}+a_1x^{n-1}y^{(n-1)}+...+a_{n-1}xy'+a_ny=f(x)"><span></span><span></span></span>
令<span class="equation-text" contenteditable="false" data-index="0" data-equation="x=e^t,则有"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="\frac{dy}{dx}=\frac{dy}{dt}\frac{dt}{dx}=\frac1x\frac{dy}{dt}"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="2" data-equation="\frac{d^2y}{dx^2}=\frac{d}{dt}(\frac{dy}{dx})\frac{dt}{dx}=\frac{1}{x}\frac{d}{dt}(\frac{1}{x}\frac{dy}{dt})=\frac{1}{x^2}(\frac{d^2y}{dt^2}-\frac{dy}{dt})"><span></span><span></span></span><br>可将方程化成线性常系数微分方程,进而求解
含边限积分的方程
<span style="font-weight: normal;">将方程求导,转化为求解相应的</span>微分方程的通解<span style="font-weight: normal;">或</span>微分方程初值问题的特解<span style="font-weight: normal;">。</span>
线性微分方程的解的性质与结构
解的叠加原理
1. 齐次微分方程的特解的线性组合依旧为其的解;<br>2. 非齐次微分方程的特解的差为对应齐次微分方程的特解;<br>3. 非齐次微分方程的特解和齐次微分方程的任意特解的和为非齐次微分方程的解
通解的结构
齐次微分方程的通解:齐次微分方程的非零特解的线性组合;<br>非齐次微分方程的通解:对应齐次微分方程的非零特解的线性组合与非齐次微分方程的特解的和
无穷级数
常数项级数
基本概念
1. 无穷级数(级数)、一般项(通项)、部分和<br>2. 部分和的极限存在,则称级数收敛,否则发散<br>3. 级数收敛时,部分和的极限称为级数的和;级数收敛时r=S-Sn称为级数的余项(余和)
收敛级数的基本性质
1. 级数收敛,则一般项的极限为0;<br>2. 收敛级数的线性运算;<br>3. 收敛级数不改变其项的次序任意加括号,并将括号内的和数作为一项,得到的新级数收敛,注意去括号后级数未必收敛;<br> 若加括号后所成的级数发散,则原来的级数也发散;<br> 若级数的一般项的极限为0,相继两项加括号所得级数收敛,则级数收敛;<br>4. 级数的敛散性与其有限项无关。
分类
几个重要级数
几何级数<span class="equation-text" contenteditable="false" data-index="0" data-equation="\sum_{n=0}^{∞}q^{n},当|q|<1时收敛,当|q|≥1时发散"><span></span><span></span></span>
p级数<span class="equation-text" contenteditable="false" data-index="0" data-equation="\sum_{n=1}^{∞}\frac{1}{n^{p}}当p>1时收敛,当p≤1时发散"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="\sum_{n=2}^{∞}\frac{1}{n^{p}ln^{q}n},当p>1时,或p=1,q>1时收敛;当p<1或p=1且q≤1时发散;"><span></span><span></span></span>
正项级数
概念、特点和收敛的充要条件
1. 正项级数:<span style="font-weight: normal;">一般项大于0的级数</span><br>2. 特点:<span style="font-weight: normal;">部分和数列单调非减</span><br>3. 收敛充要条件:<span style="font-weight: normal;">部分和数列有界</span>
敛散性判别法
比较判别法
1. 一般项更大收敛则更小收敛,更小发散则更大发散;<br>2. 一般项更低阶收敛则更高阶收敛,更高阶收敛则更低阶收敛;
与几何级数比较,比值与根值判别法
1. n+1项与n项的比值的极限小于1收敛,大于1发散,等于1不确定<br>2. 一般项的n次根式的极限小于1收敛,大于1发散,等于1不确定<br>
与p级数比较,确定无穷小Un关于1/n的阶
1. Un是1/n的高于p阶的无穷小,p>1:级数收敛;<br>2. Un是1/n的p阶或低于p阶的无穷小,p≤1:级数收敛。<br>
交错项级数
定义:<span class="equation-text" contenteditable="false" data-index="0" data-equation="u_{n}>0,则称\sum_{n=1}^{∞}(-1)^{n-1}u_{n}为交错级数"><span></span><span></span></span>
莱布尼兹判别法:<br><span style="font-weight: normal;">1. </span><span class="equation-text" contenteditable="false" data-index="0" data-equation="u_{n}≥u_{n+1},n≥N≥1;u_{n}的极限为0,则级数收敛,且其和大于0小于u_{1},余项|r_{n}|<u_{n+1}"><span></span><span></span></span>
任意项级数
1. 定义:<span style="font-weight: normal;">一般项为任意实数的级数称为任意项级数;</span><br>2. 绝对收敛与条件收敛:<span style="font-weight: 400;">若级数的一般项均取绝对值后级数收敛,则称级数绝对收敛;若级数收敛而不绝对收敛则称级数条件收敛</span><br>
1. 绝对收敛的级数一定收敛;<br>2. 条件收敛的级数的全部正项或负项构成的级数一定发散;
幂级数
函数项级数的有关概念
收敛点、收敛域、发散点、发散域、和函数
幂级数的收敛特点及其收敛域
定义
幂级数、系数、幂级数
收敛的特点
1. 阿贝尔定理:<span style="font-weight: normal;">若级数在x0收敛,则|x|<|x0|的所有x均收敛,若级数在x0发散,则|x|>|x0|的所有x均发散,</span><br><span style="font-weight: normal;">2. 存在收敛区间与收敛半径、收敛域;<br>3. 如果R为幂级数的收敛半径,则幂级数在(-R, R)上绝对收敛。</span>
收敛半径和收敛域的求法
1. 先用比值法或根值法求收敛半径,即比值或根值极限的倒数得到收敛区间,再考察收敛区间端点的敛散性
幂级数的运算与和函数的性质
1. 幂级数的公共收敛域满足如下运算:<br>(1)<span class="equation-text" contenteditable="false" data-index="0" data-equation="λ\sum\limits_{n=0}^∞a_nx^n+μ\sum\limits_{n=0}^∞b_nx^n=\sum\limits_{n=0}^∞(λa_n+μb_n)x^n"><span></span><span></span></span><br>(2)<span class="equation-text" contenteditable="false" data-index="1" data-equation="\sum\limits_{n=0}^∞a_nx^n.\sum\limits_{n=0}^∞b_nx^n=\sum\limits_{n=0}^∞c_nx^n, c_n=a_0b_n+a_1b_{n-1}+...+a_nb_0"><span></span><span></span></span><br>
2. 幂级数的和函数有如下性质:<br>(1)和函数S(x)在(-R, R)内可导,且有逐项求导公式;<br>(2)和函数S(x)在(-R, R)内可积,且有逐项积分公式;<br>(3)幂级数在收敛区间端点收敛,则幂级数在端点处可做逐项定积分,但逐项求导后的幂级数可能发散<br>(4)幂级数在收敛区间端点发散,则逐项积分后的幂级数在端点处可能收敛,但逐项求导后的幂级数一定发散
幂级数的求和与函数的幂级数展开式
1. 泰勒级数和麦克劳林级数;<br>2. 函数展成幂级数的条件:拉格朗日余项的极限为0;<br>3. 常见函数的麦克劳林展开式;<br>4. 幂级数求和与求函数的幂级数展开式的方法
傅里叶级数
基本概念
三角函数系的正交性
三角函数系<span class="equation-text" contenteditable="false" data-index="0" data-equation="\{1,cos\fracπlx,,sin\fracπlx,cos\frac{2π}lx,,sin\frac{2π}lx,...,cos\frac{nπ}lx,,sin\frac{nπ}lx,...\}"><span></span><span></span></span>在区间<span class="equation-text" contenteditable="false" data-index="1" data-equation="[-l, l]"><span></span><span></span></span>上正交
傅里叶系数与傅里叶级数
<span class="equation-text" contenteditable="false" data-index="0" data-equation="f(x):\frac{a_0}{2}+\sum_{n=1}^∞(a_ncos\frac{nπ}lx+b_nsin\frac{nπ}lx)"><span></span><span></span></span>
其中<span class="equation-text" contenteditable="false" data-index="0" data-equation="a_n=\frac{1}{l}\int_{-l}^lf(x)cos\frac{πn}lxdx,n=0,1,2,...; b_n=\frac{1}{l}\int_{-l}^lf(x)sin\frac{πn}lxdx,n=1,2,3,..."><span></span><span></span></span>
傅里也级数的收敛性
狄利克雷收敛定理:<br><span style="font-weight: normal;">函数在[-l,l]上满足:<br>(1)连续,或只有有限个间断点,且都是第一类间断点;<br>(2)只有有限个极值点,<br>则f(x)在[-l, l]上的傅里叶级数收敛,而且连续点收敛域函数值,第一类间断点收敛与左右极限的平均数,端点收敛于端点左右极限值的平均数</span>
周期函数与非周期函数的傅里叶级数
1. 非周期函数可以做周期延拓、奇延拓、偶延拓,然后再求傅里叶级数<br>2. 奇函数包括经奇延拓的函数只有sin项<br>2. 偶函数包括经偶延拓的函数只有cos项
函数f(x)的傅里叶级数展开式
f(x)定义在[-l, l]上,并满足收敛定理的狄利克雷条件,则函数可展开成傅里叶级数。
题型总结
函数性态问题
利用导数对给定函数在其定义域上求单调性区间、极值点、凹凸性区间与拐点、渐近线并作函数图形。<br>步骤:<span style="font-weight: normal;">确定函数的定义域、间断点、奇偶性、周期性;计算一二阶导数并求出为0和不存在的点并列表;<br>求出渐近线;确定曲线上的特殊点然后依照表格画图。</span><br>求渐近线的方法:<br>(1)x=a是垂直渐近线 ⇔ 该点的左极限或有极限为无穷<br>(2)x趋向于正无穷时y=b是水平渐近线 ⇔ 自变量趋向于无穷时函数的极限为b<br>(3)x趋向于正无穷时y=kx+b是斜渐近线 ⇔ <span class="equation-text" contenteditable="false" data-index="0" data-equation="\lim\limits_{x\to +\infty}\frac{f(x)}{x}=k≠0且\lim\limits_{x\to +\infty}[f(x)-kx]=b"><span></span><span></span></span>
极值最值问题
一元函数的极值(最值)问题
1. 闭区间[a, b]上连续函数f(x)的最值问题;<br>2. f(x)在区间<i>I</i>可导且仅有两个单调区间的最值问题;<br>3. 归结为求f(x)在(a, b)的驻点的最值问题;<br>4. 连续函数f(x)的极值点唯一的最值问题。
求二元函数极值点的一般步骤
1. 通过偏导为0求得所有驻点;<br>2. 对每个驻点求二阶偏导数;<br>3. 通过AC-B^2以及A的符号判断是否是极值,以及属于什么极值;<br>
多元函数的简单极值(最值)问题的解法
1. 求出函数在D内可能取得极值点(驻点和一阶偏导数不存在的点)的函数值;<br>2. 求出函数在D的边界上的最大值、最小值;<br>3. 将上面的各个函数值进行比较,最大(小)者为最大(小)值。
多元函数的条件极值(最值)问题的解法
1. 求函数z=f(x,y)在条件φ(x, y)=0下的最大值或最小值<br>(1)化为无条件极值。<span style="font-weight: normal;">若从条件φ(x, y)=0中可解出y=y(x)或x=x(y),把它带入z=f(x, y)。则可化为相应一元函数的极值问题。</span><br>(2)拉格朗日乘数法。<span style="font-weight: normal;">构造辅助函数(称为拉格朗日函数)F(x, y, λ)=f(x, y) + λφ(x, y),然后分别对x, y, λ求导数取零值,解方程。然后比较得到的最大值最小值。</span><br>2. 求函数u=f(x,y,z)在条件φ(x, y,z)=0,ψ(x, y,z)=0下的最大值或最小值<br>(1)拉格朗日乘数法。<span style="font-weight: normal;">构造辅助函数(称为拉格朗日函数)F(x, y, z, λ)=f(x, y, z) + λφ(x, y, z) + μψ(x, y, z),然后分别对x, y, λ求导数取零值,解方程。然后比较得到的最大值最小值。</span><br>
平面上曲线积分与路劲无关问题<br>微分式的原函数问题
基本定义
1. 沿任意两条分段光滑曲线<span style="font-weight: normal;">积分值相等,称曲线积分在D内与</span>路劲无关<span style="font-weight: normal;">;</span><br><span style="font-weight: normal;">2. 在D内存在u(x,y)使得du=Pdx+Qdy,则称u(x,y)时Pdx+Qdy在D内的原函数;</span><br><span style="font-weight: normal;">(2.1)u(x,y)为Pdx+Qdy的原函数,则其全部原函数为u(x,y)+C,C为所有常数;</span><br><span style="font-weight: normal;">(2.2)P(x,y),Q(x,y)在D内连续,则</span><span class="equation-text" contenteditable="false" data-index="0" data-equation="du=Pdx+Qdy((x,y)\in D)\leftrightarrows\frac{\partial u}{\partial x}=P,\frac{\partial u}{\partial y}=Q((x,y)\in D)"><span></span><span></span></span>
曲线积分与路径无关的特征
1. 对D内任意分段光滑闭曲线C,封闭曲线C的积分为0;<br>2. 在D内存在原函数u(x,y)使得du(x,y)=Pdx+Qdy;<br>3. 若积分在D内与路径无关,则<span class="equation-text" contenteditable="false" data-index="0" data-equation="\frac{\partial Q}{\partial x}=\frac{\partial P}{\partial y}((x,y)\in D)"><span></span><span></span></span>;<br>4. 若D为单连通区域,又<span class="equation-text" data-index="1" data-equation="\frac{\partial Q}{\partial x}=\frac{\partial P}{\partial y}((x,y)\in D)" contenteditable="false"><span></span><span></span></span>,则积分在D内与路径无关。
曲线积分与路径无关的判断条件
P,Q在D内连续或有一阶偏导数<br>1. 以下方法之一均可断定积分在区域D内不是与路径无关:<br>(1.1)存在分段光滑闭曲线C包含于D,沿C的积分不等于0;<br>(1.2)存在点(x,y)∈D,使得<span class="equation-text" contenteditable="false" data-index="0" data-equation="\frac{\partial Q(x,y)}{\partial x}≠\frac{\partial P(x,y)}{\partial x}"><span></span><span></span></span>;<br>2. 以下方法之一均可判断定积分在区域D内与路径无关:<br>(2.1)求得u(x,y)使得du=Pdx+Qdy,对于所有D内的点<br>(2.2)若D是单连通区域,且<span class="equation-text" contenteditable="false" data-index="1" data-equation="\frac{\partial Q}{\partial x}=\frac{\partial P}{\partial x}((x,y)\in D)"><span></span><span></span></span><br>(2.3)D=D0\{M0},若D0是单连通区域,点M0∈D0(即D是单连通区域除去一个点)。<br> 若<span class="equation-text" data-index="2" data-equation="\frac{\partial Q}{\partial x}=\frac{\partial P}{\partial x}((x,y)\in D)" contenteditable="false"><span></span><span></span></span>,又存在一条分段光滑闭曲线C0,它包围点M0且沿着C0的积分为0
曲线积分与路径无关时求积分值的方法
1. P,Q在平面区域D内连续,设积分在D内与路径无关,则可按如下方法求曲线积分:<br>(1.1)求出u,则积分值=u(B)-u(A);<br>(1.2)选取特殊路径代替弧线AB<br>
积分与路径无关时求原函数的方法
2. 设P,Q在平面区域D内连续,单端Pdx+Qdy在D内是否存在原函数等同于判断积分在D内是否与路径无关,可用如下方法求原函数:<br>(2.1)不定积分法:<br><span class="equation-text" data-index="0" data-equation="(2.1.1)\frac{\partial u}{\partial x}=P(x,y)→u=\int P(x,y)dx+C(y)" contenteditable="false"><span></span><span></span></span>;<span class="equation-text" data-index="1" data-equation="(2.1.2)由\frac{\partial u}{\partial y}=\frac{\partial}{partial y}(\int P(x,y)dx)+C'(y)=Q(x,y),求出C'(y)即可" contenteditable="false"><span></span><span></span></span>;<br>(2.2)特殊路径积分法:(先判断积分是否与路径无关,若无关则可以使用)<br>(2.3)凑微分法
应用问题化为微分方程问题
1. 利用定积分的几何意义列方程;<br>2. 利用导数的几何意义列方程;<br>3. 利用变化率满足的条件列方程;<br>4. 利用牛顿第二定律列方程;<br>5. 利用微元分析法或相应的变限积分法列方程。
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