x^2-2x（y+x）+（y+x）^2
=【x-(x+y)】^2
=y^2
（x^2+2x）^2-（2x+4y^2）^2
=(x^2+2x+2x+4y^2)(x^2+2x-2x-4y^2)
=(x+2y)^2(x+2y)(x-2y)
=(x-2y)(x+2y)^3
手机提问的朋友在客户端右上角评价点【满意】即可.