我来帮你,在线解答啊.不过我也在答,可以在线联系我啦,先沙发一下.
1=(a-b)(a^2-ab+b^2-ab)
=(a-b)(a-b)^2=(a-b)^3
2=(x+y)^2+4(x-y)^2-4(x+y)(x-y)
=[(x+y)+2(x-y)]^2=(3x-y)^2