计算：y(x-y)^2+(y-x)^3=?
问题描述：
计算：y(x-y)^2+(y-x)^3=?
答
y(x-y)^2+(y-x)^3
= y(y-x)^2+(y-x)^3
= (y-x)^2[y+(y-x)]
= (y-x)^2(2y-x)