x 的三次方减去y的三次方等于多少

题目

x 的三次方减去y的三次方等于多少
该式的规律

答案

x^3-y^3
=x^3-x^2y+y^2x-yx^2+xy^2-y^3
=x^2(x-y)+xy(y-x)+y^2(x-y)
=(x-y)(x^2-xy+y^2)