-6a2(xy)3*3ab2(y-x)
=-6a2x3y3*3ab2(y2-2xy+x2)
=-6a2x3y3*(3ab2y2-6ab2xy+3ab2x2)
=-18a3b2x3y5+36a3b2x4y4-18a3b2x5y3
结果还可以整理成-18a3b2x3y3(x2-2xy+y2)