设函数z=f(x,y)由方程e^z=xyz+cos(xy)求dz/dx ,dz/dy.求详解
问题描述:
设函数z=f(x,y)由方程e^z=xyz+cos(xy)求dz/dx ,dz/dy.求详解
答
因为x、y都为自变量,不是宗量,故此题没有全微分,应只有偏微分.详解如下:
对方程两边微分:
左边:de^z=e^z*dz
右边d[xyz+cos(xy)]=xydz+yzdx+xzdy-(sinxy)*(ydx+xdy)
则有 e^z*dz=xydz+yzdx+xzdy-(sinxy)*(ydx+xdy)
(e^z-xy)dz=(yz-sinxy)dx+(xz-sinxy)dy
dz=[(yz-sinxy)/(e^z-xy)]dx+[(xz-sinxy)/(e^z-xy)]dy
故:
∂z/∂x=(yz-sinxy)/(e^z-xy)
∂z/∂y=(xz-sinxy)/(e^z-xy)
完毕-(sinxy)*(ydx+xdy) yz-sinxy)dx +(xz-sinxy)dy 到下一行sinxy前边的y和x就没有了?谢谢哦,搞掉了,改正如下:(e^z-xy)dz=(yz-ysinxy)dx+(xz-xsinxy)dy dz=[(yz-ysinxy)/(e^z-xy)]dx+[(xz-xsinxy)/(e^z-xy)]dy故:∂z/∂x=(yz-ysinxy)/(e^z-xy)∂z/∂y=(xz-xsinxy)/(e^z-xy)