-axy-ax²y²
=-axy(1+xy)
2(x+y)²-（y+x)³
=2(x+y)²-（x+y)³
=(x+y)²(2-x-y)
4x(x-y)²+12(y-x)²
=4x(x-y)²+12(x-y)²
=4(x-y)²(x+3)
不懂得欢迎追问...