（x-1）/[(x-1）^2 -y]对x,y分别求导
问题描述：
（x-1）/[(x-1）^2 -y]对x,y分别求导
求一个稍微详细一点的过程
答
设z=（x-1）/[(x-1）^2 -y]
=(x-1)/(x²-2x+1-y)
则∂z/∂x
=[1*(x²-2x+1-y)-(x-1)(2x-2)]/(x²-2x+1-y)²
=(-x²+2x-1-y)/(x²-2x+1-y)²
∂z/∂y
=-(x-1)/(x²-2x+1-y)²*(x²-2x+1-y)'
=(x-1)/(x²-2x+1-y)²