将f(u,v)对应偏导数记为∂f/∂u=f1，∂f/∂v=f2，∂²f/(∂u∂v)=f12，∂²f/(∂v∂v)=f22，则：∂z/∂x=f1+f2/y；∂²z/(∂x∂y)=∂(f1+f2/y)/∂y=f12*∂(x/y)/∂y+(∂f2/∂y)/y-f2/y²=-xf12/y²+f22*[∂(x/y)/∂y]-f2/y²=-(xf12+xf22-f2)/y²；
