(x+y)^3(x-y)-(x+y)(x-y)^3
=(x+y)(x-y)[(x+y)^2-(x-y)^2]
=(x+y)(x-y)(x+y+x-y)(x+y-x+y)
=4xy(x+y)(x-y)
(x+y)的3次方(x-y)-(x+y)(x-y)的3次方（用分解因式计算）
(x+y)^3(x-y)-(x+y)(x-y)^3
=(x+y)(x-y)[(x+y)^2-(x-y)^2]
=(x+y)(x-y)(x+y+x-y)(x+y-x+y)
=4xy(x+y)(x-y)