这是隐函数,把z看成是x,y的函数.两边对x求导,得：e^z *z'x=yz+xy*z'x,这样得：z'x=yz/(e^z-xy)=yz/(xyz-xy)=z/(xz-x)两边对y求导,得：e^z*z'y=xz+xy*z'y,这样得：z'y=xz/(e^z-xy)=xz/(xyz-xy)=z/(yz-y)...