打开,然后再整理,就可以了~
(x2+y2)(x2-xy+y2)-2x2y2
= x4 -x3y +2x2y2 -xy3 + y4 - 2x2y2
= x4 + y4 - x3y - xy3
= (x-y)(x3-y3)
= (x-y)(x-y)(x2+xy+y2)
= (x-y)^2 * (x^2 +xy +y^2) （^表示平方）