x=x^y求导, 则dz|(2,1)-搜答案-智慧作业帮

∂z/∂x=2xy∂z/∂u=x²所以dz=2xydx+x²dy

y=2x+8/x求导

y'=2-x的-2次方×8y'=2-8x^（-2）y′=2-8/x²

z=(x+y)/(x-y) dz=?

dz=2x+y就是对z求x的导数吧

z'x=2e^(2x+y)z'y=e^(2x+y)所以dz=2e^(2x+y)dx+e^(2x+y)dy

两边同时微分：dx+2ydy+2zdz=2dzdz=1/(2-2z)dx+2y/(2-2z)dydz/dx=1/(2-2z)dz/dy=2y/(2-2z)注意：这是全微分求偏导数

令u=x^2+y^3dz/dx=dz/duXdu/dx=e^uX2x=2xe^（x^2+y^3）dz/dy=dz/duXdu/dy=e^uX3y=3ye^（x^2+y^3）考查公式(e^x)'=e^x

y=3^-x*x^2,求导

Iny=(-x)In3+2Inx(Iny)‘=-In3+2/xy'/y=-In3+2/xy'=(-In3+2/x)yy'=(-In3+2/x)[3^(-x)·(x²)]=(-x²I

∂z/∂x=2x/(1+x^2+y^2)∂z/∂y=2y/(1+x^2+y^2)dz=∂z/∂xdx+∂z/W

y=x^(x^2)求导

两边取对数lny=x^2*ln|x|两边求导y'/y=2xln|x|+x^2/xy'=y(2xln|x|+x)=x^(x^2)(2xln|x|+x)

dz=Z'xdx+Z'ydy=2xcos(x^2+y^2)dx+2ycos(x^2+y^2)dy

再问：啊不好意思搞错了。。是z=e^(x^2+y^2)，求dz，谢谢你帮我解答一下吧。。再答：

dz/dx=dz/du*(du/dx)=2u*1=2udz/dy=dz/du*(du/dy)=2u*1=2u和v没关系

y=x[arcsin (x/2)]求导

积法则+链式y'=x'[arcsin(x/2)]+x[arcsin(x/2)]'=arcsin(x/2)+x*[1/根号(1-(x/2)^2)]*(x/2)'=arcsin(x/2)+x/[2*根号(

y=x^2求导

=2x

y=x/(1+x^2)求导

dZ=[d(1/（x^2+y^2）)/dx]dx+[d(1/（x^2+y^2）)/dy]dy=-[2x/(x^2+y^2)^2dx+2y/(x^2+y^2)^2dy]

u=x^2+y∂u/∂x=2x∂u/∂y=1du=(∂u/∂x)dx+(∂u/∂y)dy=2xdx+dy

设z=ln(x+y),则dz=

dz=dx/(x+y)+dy/(x+y)

z=(2y+7)^2*ln(x^3+2)dz/dx=3x^2*(2y+7)^2/(x^3+2)dz/dy=2*(2y+7)*ln(x^3+2)