计算：y/(x的平方-xy)+2/(y-x)-x/(y的平方-xy)
问题描述：
计算：y/(x的平方-xy)+2/(y-x)-x/(y的平方-xy)
答
y/(x²-xy)+2/(y-x)-x/(y²-xy)
=[y²+2(-xy)+x²]/(x²y-xy²)
=(x-y)²/[(x-y)xy]
=(x-y)/(xy)