1.(x+y)(x-y)-(x+y)²=(x+y)[(x-y)-(x+y)]
=-2y(x+y)
2.x(x-y)-y(y-x)
=x(x-y)+y(x-y)
=(x+y)(x-y)
3.(x-y)²-4b(y-x)
=(x-y)²+4b(x-y)
=(x-y)(x-y+4b)
4.a(x-a)(x+y)²-b(x-a)²(x+y)
=(x-a)(x+y)[a(x+y)-b(x-a)]
=(x-a)(x+y)(ax+ay-bx+ab)
如果不懂,请Hi我,祝学习愉快!昂。。谢谢，可不可以把第一题的过程解得详细点？？提取公因式x+y即可，你看我的过程。