高等数学(第七版)同济大学 习题2

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高等数学(第七版)同济大学 习题2

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高等数学(第七版)同济大学 习题2-2

 

1.   推 导 余 切 函 数 及 余 割 函 数 的 导 数 公 式 : \begin{aligned}&1. \ 推导余切函数及余割函数的导数公式:&\end{aligned} ​1. 推导余切函数及余割函数的导数公式:​​

   ( c o t   x ) ′ = − c s c 2   x ,               ( c s c   x ) ′ = − c s c   x   c o t   x \begin{aligned} &\ \ (cot\ x)'=-csc^2\ x,\ \ \ \ \ \ \ \ \ \ \ \ \ (csc\ x)'=-csc\ x\ cot\ x & \end{aligned} ​  (cot x)′=−csc2 x,             (csc x)′=−csc x cot x​​

解:

   ( c o t   x ) ′ = ( c o s   x s i n   x ) ′ = ( c o s   x ) ′ s i n   x − c o s   x ( s i n   x ) ′ s i n 2   x = − s i n 2   x − c o s 2   x s i n 2 x = − 1 s i n 2   x = − c s c 2   x    ( c s c   x ) ′ = ( 1 s i n   x ) ′ = 1 ′ s i n   x − 1 ⋅ ( s i n   x ) ′ s i n 2   x = − c o s   x s i n 2   x = − 1 s i n   x ⋅ c o s   x s i n   x = − c s c   x   c o t   x \begin{aligned} &\ \ (cot\ x)'=\left(\frac{cos\ x}{sin\ x}\right)'=\frac{(cos\ x)'sin\ x-cos\ x(sin\ x)'}{sin^2\ x}=\frac{-sin^2\ x-cos^2\ x}{sin^2 x}=-\frac{1}{sin^2\ x}=-csc^2\ x\\\\ &\ \ (csc\ x)'=\left(\frac{1}{sin\ x}\right)'=\frac{1'sin\ x-1 \cdot (sin\ x)'}{sin^2\ x}=-\frac{cos\ x}{sin^2\ x}=-\frac{1}{sin\ x} \cdot \frac{cos\ x}{sin\ x}=-csc\ x\ cot\ x & \end{aligned} ​  (cot x)′=(sin xcos x​)′=sin2 x(cos x)′sin x−cos x(sin x)′​=sin2x−sin2 x−cos2 x​=−sin2 x1​=−csc2 x  (csc x)′=(sin x1​)′=sin2 x1′sin x−1⋅(sin x)′​=−sin2 xcos x​=−sin x1​⋅sin xcos x​=−csc x cot x​​

2.   求 下 列 函 数 的 导 数 : \begin{aligned}&2. \ 求下列函数的导数:&\end{aligned} ​2. 求下列函数的导数:​​

   ( 1 )    y = x 3 + 7 x 4 − 2 x + 12 ;                  ( 2 )    y = 5 x 3 − 2 x + 3 e x ;    ( 3 )    y = 2 t a n   x + s e c   x − 1 ;                 ( 4 )    y = s i n   x ⋅ c o s   x ;    ( 5 )    y = x 2 l n   x ;                                      ( 6 )    y = 3 e x c o s   x ;    ( 7 )    y = l n   x x ;                                         ( 8 )    y = e x x 2 + l n   3 ;    ( 9 )    y = x 2 l n   x c o s   x ;                             ( 10 )    s = 1 + s i n   t 1 + c o s   t \begin{aligned} &\ \ (1)\ \ y=x^3+\frac{7}{x^4}-\frac{2}{x}+12;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (2)\ \ y=5x^3-2^x+3e^x;\\\\ &\ \ (3)\ \ y=2tan\ x+sec\ x-1;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (4)\ \ y=sin\ x \cdot cos\ x;\\\\ &\ \ (5)\ \ y=x^2ln\ x;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (6)\ \ y=3e^xcos\ x;\\\\ &\ \ (7)\ \ y=\frac{ln\ x}{x};\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (8)\ \ y=\frac{e^x}{x^2}+ln\ 3;\\\\ &\ \ (9)\ \ y=x^2ln\ xcos\ x;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (10)\ \ s=\frac{1+sin\ t}{1+cos\ t} & \end{aligned} ​  (1)  y=x3+x47​−x2​+12;                (2)  y=5x3−2x+3ex;  (3)  y=2tan x+sec x−1;               (4)  y=sin x⋅cos x;  (5)  y=x2ln x;                                    (6)  y=3excos x;  (7)  y=xln x​;                                       (8)  y=x2ex​+ln 3;  (9)  y=x2ln xcos x;                           (10)  s=1+cos t1+sin t​​​

解:

   ( 1 )   y ′ = ( x 3 + 7 x − 4 − 2 x − 1 + 12 ) ′ = 3 x 2 − 28 x 5 + 2 x 2    ( 2 )   y ′ = ( 5 x 3 − 2 x + 3 e x ) ′ = 15 x 2 − 2 x l n   2 + 3 e x    ( 3 )   y ′ = ( 2 t a n   x + s e c   x − 1 ) ′ = 2 s e c 2   x + s e c   x t a n   x    ( 4 )   y ′ = ( s i n   x ⋅ c o s   x ) ′ = ( s i n   x ) ′ c o s   x + s i n   x ( c o s   x ) ′ = c o s 2   x − s i n 2   x = c o s   2 x    ( 5 )   y ′ = ( x 2 l n   x ) ′ = ( x 2 ) ′ l n   x + x 2 ( l n   x ) ′ = 2 x l n   x + x    ( 6 )   y ′ = ( 3 e x c o s   x ) ′ = 3 e x c o s   x + 3 e x ( c o s   x ) ′ = 3 e x c o s   x − 3 e x s i n   x = 3 e x ( c o s   x − s i n   x )    ( 7 )   y ′ = ( l n   x x ) ′ = ( l n   x ) ′ x − l n   x ( x ) ′ x 2 = 1 − l n   x x 2    ( 8 )   y ′ = ( e x x 2 + l n   3 ) ′ = ( e x x 2 ) ′ + ( l n   3 ) ′ = e x x 2 − 2 e x x x 4 = e x ( x − 2 ) x 3    ( 9 )   y ′ = ( x 2 l n   x c o s   x ) ′ = 2 x l n   x c o s   x + x c o s   x − x 2 l n   x s i n   x    ( 10 )   s ′ = ( 1 + s i n   t 1 + c o s   t ) ′ = ( 1 + s i n   t ) ′ ( 1 + c o s   t ) − ( 1 + s i n   t ) ( 1 + c o s   t ) ′ ( 1 + c o s   t ) 2 = s i n   t + c o s   t + 1 ( 1 + c o s   t ) 2 \begin{aligned} &\ \ (1)\ y'=(x^3+7x^{-4}-2x^{-1}+12)'=3x^2-\frac{28}{x^5}+\frac{2}{x^2}\\\\ &\ \ (2)\ y'=(5x^3-2^x+3e^x)'=15x^2-2^xln\ 2+3e^x\\\\ &\ \ (3)\ y'=(2tan\ x+sec\ x-1)'=2sec^2\ x+sec\ xtan\ x\\\\ &\ \ (4)\ y'=(sin\ x \cdot cos\ x)'=(sin\ x)'cos\ x+sin\ x(cos\ x)'=cos^2\ x-sin^2\ x=cos\ 2x\\\\ &\ \ (5)\ y'=(x^2ln\ x)'=(x^2)'ln\ x+x^2(ln\ x)'=2xln\ x+x\\\\ &\ \ (6)\ y'=(3e^xcos\ x)'=3e^xcos\ x+3e^x(cos\ x)'=3e^xcos\ x-3e^xsin\ x=3e^x(cos\ x-sin\ x)\\\\ &\ \ (7)\ y'=\left(\frac{ln\ x}{x}\right)'=\frac{(ln\ x)'x-ln\ x(x)'}{x^2}=\frac{1-ln\ x}{x^2}\\\\ &\ \ (8)\ y'=\left(\frac{e^x}{x^2}+ln\ 3\right)'=\left(\frac{e^x}{x^2}\right)'+(ln\ 3)'=\frac{e^xx^2-2e^xx}{x^4}=\frac{e^x(x-2)}{x^3}\\\\ &\ \ (9)\ y'=(x^2ln\ xcos\ x)'=2xln\ xcos\ x+xcos\ x-x^2ln\ xsin\ x\\\\ &\ \ (10)\ s'=\left(\frac{1+sin\ t}{1+cos\ t}\right)'=\frac{(1+sin\ t)'(1+cos\ t)-(1+sin\ t)(1+cos\ t)'}{(1+cos\ t)^2}=\frac{sin\ t+cos\ t+1}{(1+cos\ t)^2} & \end{aligned} ​  (1) y′=(x3+7x−4−2x−1+12)′=3x2−x528​+x22​  (2) y′=(5x3−2x+3ex)′=15x2−2xln 2+3ex  (3) y′=(2tan x+sec x−1)′=2sec2 x+sec xtan x  (4) y′=(sin x⋅cos x)′=(sin x)′cos x+sin x(cos x)′=cos2 x−sin2 x=cos 2x  (5) y′=(x2ln x)′=(x2)′ln x+x2(ln x)′=2xln x+x  (6) y′=(3excos x)′=3excos x+3ex(cos x)′=3excos x−3exsin x=3ex(cos x−sin x)  (7) y′=(xln x​)′=x2(ln x)′x−ln x(x)′​=x21−ln x​  (8) y′=(x2ex​+ln 3)′=(x2ex​)′+(ln 3)′=x4exx2−2exx​=x3ex(x−2)​  (9) y′=(x2ln xcos x)′=2xln xcos x+xcos x−x2ln xsin x  (10) s′=(1+cos t1+sin t​)′=(1+cos t)2(1+sin t)′(1+cos t)−(1+sin t)(1+cos t)′​=(1+cos t)2sin t+cos t+1​​​

3.   求 下 列 函 数 在 给 定 点 处 的 导 数 : \begin{aligned}&3. \ 求下列函数在给定点处的导数:&\end{aligned} ​3. 求下列函数在给定点处的导数:​​

   ( 1 )    y = s i n   x − c o s   x , 求 y ′ ∣ x = π 6 和 y ′ ∣ x = π 4 ;    ( 2 )    ρ = θ s i n   θ + 1 2 c o s   θ , 求 d ρ d θ ∣ θ = π 4 ;    ( 3 )    f ( x ) = 3 5 − x + x 2 5 , 求 f ′ ( 0 ) 和 f ′ ( 2 ) . \begin{aligned} &\ \ (1)\ \ y=sin\ x-cos\ x,求y'\bigg|_{x=\frac{\pi}{6}}和y'\bigg|_{x=\frac{\pi}{4}};\\\\ &\ \ (2)\ \ \rho=\theta sin\ \theta+\frac{1}{2}cos\ \theta,求\frac{d\rho}{d\theta}\bigg|_{\theta=\frac{\pi}{4}};\\\\ &\ \ (3)\ \ f(x)=\frac{3}{5-x}+\frac{x^2}{5},求f'(0)和f'(2). & \end{aligned} ​  (1)  y=sin x−cos x,求y′∣∣∣∣​x=6π​​和y′∣∣∣∣​x=4π​​;  (2)  ρ=θsin θ+21​cos θ,求dθdρ​∣∣∣∣​θ=4π​​;  (3)  f(x)=5−x3​+5x2​,求f′(0)和f′(2).​​

解:

   ( 1 )   y ′ = ( s i n   x − c o s   x ) ′ = c o s   x + s i n   x , y ′ ∣ x = π 6 = c o s   π 6 + s i n   π 6 = 3 + 1 2 , y ′ ∣ x = π 4 = c o s   π 4 + s i n   π 4 = 2    ( 2 )   ρ ′ = ( θ s i n   θ + 1 2 c o s   θ ) ′ = s i n   θ + θ c o s   θ − 1 2 s i n   θ = 1 2 s i n   θ + θ c o s   θ ,         d ρ d θ ∣ θ = π 4 = 1 2 s i n   π 4 + π 4 c o s   π 4 = 2 4 ( 1 + π 2 )    ( 3 )   f ′ ( x ) = ( 3 5 − x + x 2 5 ) ′ = ( 3 5 − x ) ′ + ( x 2 5 ) ′ = 3 ( 5 − x ) 2 + 2 5 x , f ′ ( 0 ) = 3 25 , f ′ ( 2 ) = 17 15 \begin{aligned} &\ \ (1)\ y'=(sin\ x-cos\ x)'=cos\ x+sin\ x,y'\bigg|_{x=\frac{\pi}{6}}=cos\ \frac{\pi}{6}+sin\ \frac{\pi}{6}=\frac{\sqrt{3}+1}{2},y'\bigg|_{x=\frac{\pi}{4}}=cos\ \frac{\pi}{4}+sin\ \frac{\pi}{4}=\sqrt{2}\\\\ &\ \ (2)\ \rho'=(\theta sin\ \theta+\frac{1}{2}cos\ \theta)'=sin\ \theta+\theta cos\ \theta-\frac{1}{2}sin\ \theta=\frac{1}{2}sin\ \theta+\theta cos\ \theta,\\\\ &\ \ \ \ \ \ \ \frac{d\rho}{d\theta}\bigg|_{\theta=\frac{\pi}{4}}=\frac{1}{2}sin\ \frac{\pi}{4}+\frac{\pi}{4}cos\ \frac{\pi}{4}=\frac{\sqrt{2}}{4}\left(1+\frac{\pi}{2}\right)\\\\ &\ \ (3)\ f'(x)=\left(\frac{3}{5-x}+\frac{x^2}{5}\right)'=\left(\frac{3}{5-x}\right)'+\left(\frac{x^2}{5}\right)'=\frac{3}{(5-x)^2}+\frac{2}{5}x,f'(0)=\frac{3}{25},f'(2)=\frac{17}{15} & \end{aligned} ​  (1) y′=(sin x−cos x)′=cos x+sin x,y′∣∣∣∣​x=6π​​=cos 6π​+sin 6π​=23 ​+1​,y′∣∣∣∣​x=4π​​=cos 4π​+sin 4π​=2 ​  (2) ρ′=(θsin θ+21​cos θ)′=sin θ+θcos θ−21​sin θ=21​sin θ+θcos θ,       dθdρ​∣∣∣∣​θ=4π​​=21​sin 4π​+4π​cos 4π​=42 ​​(1+2π​)  (3) f′(x)=(5−x3​+5x2​)′=(5−x3​)′+(5x2​)′=(5−x)23​+52​x,f′(0)=253​,f′(2)=1517​​​

4.   以 初 速 度 v 0 竖 直 上 抛 的 物 体 , 其 上 升 高 度 s 与 时 间 t 的 关 系 是 s = v 0 t − 1 2 g t 2 . 求 : \begin{aligned}&4. \ 以初速度v_0竖直上抛的物体,其上升高度s与时间t的关系是s=v_0t-\frac{1}{2}gt^2.求:&\end{aligned} ​4. 以初速度v0​竖直上抛的物体,其上升高度s与时间t的关系是s=v0​t−21​gt2.求:​​

   ( 1 )    该 物 体 的 速 度 v ( t ) ;                          ( 2 )    该 物 体 达 到 最 高 点 的 时 刻 . \begin{aligned} &\ \ (1)\ \ 该物体的速度v(t);\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (2)\ \ 该物体达到最高点的时刻. & \end{aligned} ​  (1)  该物体的速度v(t);                        (2)  该物体达到最高点的时刻.​​

解:

   ( 1 )   v ( t ) = s ′ = ( v 0 t − 1 2 g t 2 ) ′ = v 0 − g t    ( 2 )   最 高 点 处 v = 0 , v 0 − g t = 0 , 即 t = v 0 g \begin{aligned} &\ \ (1)\ v(t)=s'=(v_0t-\frac{1}{2}gt^2)'=v_0-gt\\\\ &\ \ (2)\ 最高点处v=0,v_0-gt=0,即t=\frac{v_0}{g} & \end{aligned} ​  (1) v(t)=s′=(v0​t−21​gt2)′=v0​−gt  (2) 最高点处v=0,v0​−gt=0,即t=gv0​​​​

5.   求 曲 线 y = 2 s i n   x + x 2 上 横 坐 标 为 x = 0 的 点 处 的 切 线 方 程 和 法 线 方 程 。 \begin{aligned}&5. \ 求曲线y=2sin\ x+x^2上横坐标为x=0的点处的切线方程和法线方程。&\end{aligned} ​5. 求曲线y=2sin x+x2上横坐标为x=0的点处的切线方程和法线方程。​​ 解:

   y ′ = ( 2 s i n   x + x 2 ) ′ = 2 c o s   x + 2 x , 当 x = 0 时 , y ′ = 2 , 斜 率 为 2 ,    又 因 曲 线 上 x = 0 时 , y = 0 , 所 以 切 线 方 程 为 y − 0 = 2 ( x − 0 ) , 2 x − y = 0 。    法 线 方 程 为 y − 0 = − 1 2 ( x − 0 ) , x + 2 y = 0 \begin{aligned} &\ \ y'=(2sin\ x+x^2)'=2cos\ x+2x,当x=0时,y'=2,斜率为2,\\\\ &\ \ 又因曲线上x=0时,y=0,所以切线方程为y-0=2(x-0),2x-y=0。\\\\ &\ \ 法线方程为y-0=-\frac{1}{2}(x-0),x+2y=0 & \end{aligned} ​  y′=(2sin x+x2)′=2cos x+2x,当x=0时,y′=2,斜率为2,  又因曲线上x=0时,y=0,所以切线方程为y−0=2(x−0),2x−y=0。  法线方程为y−0=−21​(x−0),x+2y=0​​

6.   求 下 列 函 数 的 导 数 : \begin{aligned}&6. \ 求下列函数的导数:&\end{aligned} ​6. 求下列函数的导数:​​

   ( 1 )    y = ( 2 x + 5 ) 4 ;                                 ( 2 )    y = c o s ( 4 − 3 x ) ;    ( 3 )    y = e − 3 x 2 ;                                        ( 4 )    y = l n ( 1 + x 2 ) ;    ( 5 )    y = s i n 2   x ;                                      ( 6 )    y = a 2 − x 2 ;    ( 7 )    y = t a n   x 2 ;                                      ( 8 )    y = a r c t a n ( e x ) ;    ( 9 )    y = ( a r c s i n   x ) 2 ;                             ( 10 )    y = l n   c o s   x \begin{aligned} &\ \ (1)\ \ y=(2x+5)^4;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (2)\ \ y=cos(4-3x);\\\\ &\ \ (3)\ \ y=e^{-3x^2};\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (4)\ \ y=ln(1+x^2);\\\\ &\ \ (5)\ \ y=sin^2\ x;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (6)\ \ y=\sqrt{a^2-x^2};\\\\ &\ \ (7)\ \ y=tan\ x^2;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (8)\ \ y=arctan(e^x);\\\\ &\ \ (9)\ \ y=(arcsin\ x)^2;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (10)\ \ y=ln\ cos\ x & \end{aligned} ​  (1)  y=(2x+5)4;                               (2)  y=cos(4−3x);  (3)  y=e−3x2;                                      (4)  y=ln(1+x2);  (5)  y=sin2 x;                                    (6)  y=a2−x2 ​;  (7)  y=tan x2;                                    (8)  y=arctan(ex);  (9)  y=(arcsin x)2;                           (10)  y=ln cos x​​

解:

   ( 1 )   设 u = 2 x + 5 , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 4 ( 2 x + 5 ) 3 ⋅ 2 = 8 ( 2 x + 5 ) 3    ( 2 )   设 u = 4 − 3 x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = − s i n   ( 4 − 3 x ) ⋅ ( − 3 ) = 3 s i n   ( 4 − 3 x )    ( 3 )   设 u = − 3 x 2 , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = e − 3 x 2 ⋅ ( − 6 x ) = − 6 x e − 3 x 2    ( 4 )   设 u = 1 + x 2 , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 1 + x 2 ⋅ 2 x = 2 x 1 + x 2    ( 5 )   设 u = s i n   x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 2 s i n   x ⋅ c o s   x = s i n   2 x    ( 6 )   设 u = a 2 − x 2 , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 2 a 2 − x 2 ⋅ ( − 2 x ) = − x a 2 − x 2    ( 7 )   设 u = x 2 , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = s e c 2   x 2 ⋅ ( 2 x ) = 2 x s e c 2   x 2    ( 8 )   设 u = e x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 1 + e 2 x ⋅ e x = e x 1 + e 2 x    ( 9 )   设 u = a r c s i n   x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 2 a r c s i n   x ⋅ 1 1 − x 2 = 2 1 − x 2 a r c s i n   x    ( 10 )   设 u = c o s   x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 c o s   x ⋅ ( − s i n   x ) = − s i n   x c o s   x = − t a n   x \begin{aligned} &\ \ (1)\ 设u=2x+5,则y'(x)=f'(u) \cdot g'(x)=4(2x+5)^3 \cdot 2=8(2x+5)^3\\\\ &\ \ (2)\ 设u=4-3x,则y'(x)=f'(u) \cdot g'(x)=-sin\ (4-3x) \cdot (-3)=3sin\ (4-3x)\\\\ &\ \ (3)\ 设u=-3x^2,则y'(x)=f'(u) \cdot g'(x)=e^{-3x^2} \cdot (-6x)=-6xe^{-3x^2}\\\\ &\ \ (4)\ 设u=1+x^2,则y'(x)=f'(u) \cdot g'(x)=\frac{1}{1+x^2} \cdot 2x=\frac{2x}{1+x^2}\\\\ &\ \ (5)\ 设u=sin\ x,则y'(x)=f'(u) \cdot g'(x)=2sin\ x \cdot cos\ x=sin\ 2x\\\\ &\ \ (6)\ 设u=a^2-x^2,则y'(x)=f'(u) \cdot g'(x)=\frac{1}{2\sqrt{a^2-x^2}} \cdot (-2x)=-\frac{x}{\sqrt{a^2-x^2}}\\\\ &\ \ (7)\ 设u=x^2,则y'(x)=f'(u) \cdot g'(x)=sec^2\ x^2 \cdot (2x)=2xsec^2\ x^2\\\\ &\ \ (8)\ 设u=e^x,则y'(x)=f'(u) \cdot g'(x)=\frac{1}{1+e^{2x}} \cdot e^x=\frac{e^x}{1+e^{2x}}\\\\ &\ \ (9)\ 设u=arcsin\ x,则y'(x)=f'(u) \cdot g'(x)=2arcsin\ x \cdot \frac{1}{\sqrt{1-x^2}}=\frac{2}{\sqrt{1-x^2}}arcsin\ x\\\\ &\ \ (10)\ 设u=cos\ x,则y'(x)=f'(u) \cdot g'(x)=\frac{1}{cos\ x} \cdot (-sin\ x)=-\frac{sin\ x}{cos\ x}=-tan\ x & \end{aligned} ​  (1) 设u=2x+5,则y′(x)=f′(u)⋅g′(x)=4(2x+5)3⋅2=8(2x+5)3  (2) 设u=4−3x,则y′(x)=f′(u)⋅g′(x)=−sin (4−3x)⋅(−3)=3sin (4−3x)  (3) 设u=−3x2,则y′(x)=f′(u)⋅g′(x)=e−3x2⋅(−6x)=−6xe−3x2  (4) 设u=1+x2,则y′(x)=f′(u)⋅g′(x)=1+x21​⋅2x=1+x22x​  (5) 设u=sin x,则y′(x)=f′(u)⋅g′(x)=2sin x⋅cos x=sin 2x  (6) 设u=a2−x2,则y′(x)=f′(u)⋅g′(x)=2a2−x2 ​1​⋅(−2x)=−a2−x2 ​x​  (7) 设u=x2,则y′(x)=f′(u)⋅g′(x)=sec2 x2⋅(2x)=2xsec2 x2  (8) 设u=ex,则y′(x)=f′(u)⋅g′(x)=1+e2x1​⋅ex=1+e2xex​  (9) 设u=arcsin x,则y′(x)=f′(u)⋅g′(x)=2arcsin x⋅1−x2 ​1​=1−x2 ​2​arcsin x  (10) 设u=cos x,则y′(x)=f′(u)⋅g′(x)=cos x1​⋅(−sin x)=−cos xsin x​=−tan x​​

7.   求 下 列 函 数 的 导 数 : \begin{aligned}&7. \ 求下列函数的导数:&\end{aligned} ​7. 求下列函数的导数:​​

   ( 1 )    y = a r c s i n ( 1 − 2 x ) ;                       ( 2 )    y = 1 1 − x 2 ;    ( 3 )    y = e − x 2 c o s   3 x ;                               ( 4 )    y = a r c c o s   1 x ;    ( 5 )    y = 1 − l n   x 1 + l n   x ;                                  ( 6 )    y = s i n   2 x x ;    ( 7 )    y = a r c s i n   x ;                               ( 8 )    y = l n ( x + a 2 + x 2 ) ;    ( 9 )    y = l n ( s e c   x + t a n   x ) ;                   ( 10 )    y = l n ( c s c   x − c o t   x ) \begin{aligned} &\ \ (1)\ \ y=arcsin(1-2x);\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (2)\ \ y=\frac{1}{\sqrt{1-x^2}};\\\\ &\ \ (3)\ \ y=e^{-\frac{x}{2}}cos\ 3x;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (4)\ \ y=arccos\ \frac{1}{x};\\\\ &\ \ (5)\ \ y=\frac{1-ln\ x}{1+ln\ x};\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (6)\ \ y=\frac{sin\ 2x}{x};\\\\ &\ \ (7)\ \ y=arcsin\ \sqrt{x};\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (8)\ \ y=ln(x+\sqrt{a^2+x^2});\\\\ &\ \ (9)\ \ y=ln(sec\ x+tan\ x);\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (10)\ \ y=ln(csc\ x-cot\ x) & \end{aligned} ​  (1)  y=arcsin(1−2x);                     (2)  y=1−x2 ​1​;  (3)  y=e−2x​cos 3x;                             (4)  y=arccos x1​;  (5)  y=1+ln x1−ln x​;                                (6)  y=xsin 2x​;  (7)  y=arcsin x ​;                             (8)  y=ln(x+a2+x2 ​);  (9)  y=ln(sec x+tan x);                 (10)  y=ln(csc x−cot x)​​

解:

   ( 1 )   设 u = 1 − 2 x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 1 − ( 1 − 2 x ) 2 ⋅ ( − 2 ) = − 1 x − x 2    ( 2 )   设 u = 1 − x 2 , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = − 1 2 ( 1 − x 2 ) − 3 2 ⋅ ( − 2 x ) = x ( 1 − x 2 ) − 3 2    ( 3 )   y ′ ( x ) = ( e − x 2 ) ′ c o s   3 x + e − x 2 ( c o s   3 x ) ′ , 设 u = − x 2 , v = 3 x , 则 y ′ ( x ) = − 1 2 e − x 2 c o s   3 x − 3 e − x 2 s i n   3 x =          − 1 2 e − x 2 ( c o s   3 x + 6 s i n   3 x )    ( 4 )   设 u = 1 x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = − 1 1 − 1 x 2 ⋅ ( − 1 x 2 ) = ∣ x ∣ x 2 x 2 − 1    ( 5 )   y ′ ( x ) = ( 1 − l n   x ) ′ ( 1 + l n   x ) − ( 1 − l n   x ) ( 1 + l n   x ) ′ ( 1 + l n   x ) 2 = − 1 − l n   x − 1 + l n   x x ( 1 + l n   x ) 2 = − 2 x ( 1 + l n   x ) 2    ( 6 )   y ′ ( x ) = ( s i n   2 x ) ′ x − s i n   2 x ( x ) ′ x 2 = 2 x c o s   2 x − s i n   2 x x 2    ( 7 )   设 u = x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 1 − x ⋅ 1 2 x = 1 2 x − x 2    ( 8 )   设 u = x + a 2 + x 2 , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 x + a 2 + x 2 ⋅ ( x + a 2 + x 2 ) ′ =           1 x + a 2 + x 2 ⋅ ( 1 + x a 2 + x 2 ) = 1 a 2 + x 2    ( 9 )   设 u = s e c   x + t a n   x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 s e c   x + t a n   x ⋅ ( s e c   x + t a n   x ) ′ =           1 s e c   x + t a n   x ⋅ ( s e c   x t a n   x + s e c 2   x ) = s e c   x    ( 10 )   设 u = c s c   x − c o t   x , 则 y ′ ( x ) = f ′ ( u ) ⋅ g ′ ( x ) = 1 c s c   x − c o t   x ⋅ ( c s c   x − c o t   x ) ′ =           1 c s c   x − c o t   x ⋅ ( − c s c   x c o t   x + c s c 2   x ) = c s c   x \begin{aligned} &\ \ (1)\ 设u=1-2x,则y'(x)=f'(u) \cdot g'(x)=\frac{1}{\sqrt{1-(1-2x)^2}} \cdot (-2)=-\frac{1}{\sqrt{x-x^2}}\\\\ &\ \ (2)\ 设u=1-x^2,则y'(x)=f'(u) \cdot g'(x)=-\frac{1}{2}(1-x^2)^{-\frac{3}{2}} \cdot (-2x)=x(1-x^2)^{-\frac{3}{2}}\\\\ &\ \ (3)\ y'(x)=(e^{-\frac{x}{2}})'cos\ 3x+e^{-\frac{x}{2}}(cos\ 3x)',设u=-\frac{x}{2},v=3x,则y'(x)=-\frac{1}{2}e^{-\frac{x}{2}}cos\ 3x-3e^{-\frac{x}{2}}sin\ 3x=\\\\ &\ \ \ \ \ \ \ \ -\frac{1}{2}e^{-\frac{x}{2}}(cos\ 3x+6sin\ 3x)\\\\ &\ \ (4)\ 设u=\frac{1}{x},则y'(x)=f'(u) \cdot g'(x)=-\frac{1}{\sqrt{1-\frac{1}{x^2}}} \cdot (-\frac{1}{x^2})=\frac{|x|}{x^2\sqrt{x^2-1}}\\\\ &\ \ (5)\ y'(x)=\frac{(1-ln\ x)'(1+ln\ x)-(1-ln\ x)(1+ln\ x)'}{(1+ln\ x)^2}=\frac{\frac{-1-ln\ x-1+ln\ x}{x}}{(1+ln\ x)^2}=-\frac{2}{x(1+ln\ x)^2}\\\\ &\ \ (6)\ y'(x)=\frac{(sin\ 2x)'x-sin\ 2x(x)'}{x^2}=\frac{2xcos\ 2x-sin\ 2x}{x^2}\\\\ &\ \ (7)\ 设u=\sqrt{x},则y'(x)=f'(u) \cdot g'(x)=\frac{1}{\sqrt{1-x}} \cdot \frac{1}{2\sqrt{x}}=\frac{1}{2\sqrt{x-x^2}}\\\\ &\ \ (8)\ 设u=x+\sqrt{a^2+x^2},则y'(x)=f'(u) \cdot g'(x)=\frac{1}{x+\sqrt{a^2+x^2}} \cdot (x+\sqrt{a^2+x^2})'=\\\\ &\ \ \ \ \ \ \ \ \ \frac{1}{x+\sqrt{a^2+x^2}} \cdot \left(1+\frac{x}{\sqrt{a^2+x^2}}\right)=\frac{1}{\sqrt{a^2+x^2}}\\\\ &\ \ (9)\ 设u=sec\ x+tan\ x,则y'(x)=f'(u) \cdot g'(x)=\frac{1}{sec\ x+tan\ x} \cdot (sec\ x+tan\ x)'=\\\\ &\ \ \ \ \ \ \ \ \ \frac{1}{sec\ x+tan\ x} \cdot (sec\ xtan\ x+sec^2\ x)=sec\ x\\\\ &\ \ (10)\ 设u=csc\ x-cot\ x,则y'(x)=f'(u) \cdot g'(x)=\frac{1}{csc\ x-cot\ x} \cdot (csc\ x -cot\ x)'=\\\\ &\ \ \ \ \ \ \ \ \ \frac{1}{csc\ x-cot\ x} \cdot (-csc\ xcot\ x+csc^2\ x)=csc\ x & \end{aligned} ​  (1) 设u=1−2x,则y′(x)=f′(u)⋅g′(x)=1−(1−2x)2 ​1​⋅(−2)=−x−x2 ​1​  (2) 设u=1−x2,则y′(x)=f′(u)⋅g′(x)=−21​(1−x2)−23​⋅(−2x)=x(1−x2)−23​  (3) y′(x)=(e−2x​)′cos 3x+e−2x​(cos 3x)′,设u=−2x​,v=3x,则y′(x)=−21​e−2x​cos 3x−3e−2x​sin 3x=        −21​e−2x​(cos 3x+6sin 3x)  (4) 设u=x1​,则y′(x)=f′(u)⋅g′(x)=−1−x21​ ​1​⋅(−x21​)=x2x2−1 ​∣x∣​  (5) y′(x)=(1+ln x)2(1−ln x)′(1+ln x)−(1−ln x)(1+ln x)′​=(1+ln x)2x−1−ln x−1+ln x​​=−x(1+ln x)22​  (6) y′(x)=x2(sin 2x)′x−sin 2x(x)′​=x22xcos 2x−sin 2x​  (7) 设u=x ​,则y′(x)=f′(u)⋅g′(x)=1−x ​1​⋅2x ​1​=2x−x2 ​1​  (8) 设u=x+a2+x2 ​,则y′(x)=f′(u)⋅g′(x)=x+a2+x2 ​1​⋅(x+a2+x2 ​)′=         x+a2+x2 ​1​⋅(1+a2+x2 ​x​)=a2+x2 ​1​  (9) 设u=sec x+tan x,则y′(x)=f′(u)⋅g′(x)=sec x+tan x1​⋅(sec x+tan x)′=         sec x+tan x1​⋅(sec xtan x+sec2 x)=sec x  (10) 设u=csc x−cot x,则y′(x)=f′(u)⋅g′(x)=csc x−cot x1​⋅(csc x−cot x)′=         csc x−cot x1​⋅(−csc xcot x+csc2 x)=csc x​​



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