(x-y)(x2+xy+y2)-xy(y-x)
问题描述：
(x-y)(x2+xy+y2)-xy(y-x)
答
(x-y)(x2+xy+y2)-xy(y-x)
=(x-y)(x²＋xy＋y²＋xy)
=(x-y)(x+y)²