设z=f(u，υ，y)=eusinv+y3，其中u=2x+u，υ=xy，求∂z/∂x，∂z/∂y．
【正确答案】：∂z/∂x=∂f/∂u•∂u/∂x+∂f/∂υ•∂υ/∂x =eusinυ•2+eucosυ•y =e2x+y[2sin(xy)+ycos(xy)]， ∂z/∂y=∂f/∂u•∂u/∂y+∂f/∂υ•∂υ/∂y+∂f/∂y =eusinv•1+eucos•x+3y2 =e2x+y[sin(xy)+xcos(xy)]+3y2．
