化简 (x^2+2y^2)(x-2y)+2xy(x-y)

问题描述:

化简 (x^2+2y^2)(x-2y)+2xy(x-y)

x^3-4y^3

原式=x^3-2x^2y+2xy^2-4y^3+2x^2y-2xy^2
=x^3-4y^3