因式分解x^3+x^2y-xy^2-y^3
问题描述：
因式分解x^3+x^2y-xy^2-y^3
答
x^3+x^2y-xy^2-y^3
=（x-y）(x^2+xy+y^2)+xy(x-y)
=(x-y)(x^2+y^2+2xy)
=(x-y)(x+y)^2