计算：（x-y）分之2+y分之x-x分之1
问题描述：
计算：（x-y）分之2+y分之x-x分之1
答
通分:
[2xy+x(x-y)x-(x-y)y]/[xy(x-y)]
=(2xy+x³-x²y-xy+y²)/[xy(x-y)]
=(xy+x³-x²y+y²)/[xy(x-y)]