(x+y)(x-y)-(x+y)²怎么提公因式

问题描述:

(x+y)(x-y)-(x+y)²怎么提公因式

(x+y)(x-y)-(x+y)²
=(x+y)[(x-y)-(x+y)]
=(x+y)(-2y)
=-2y(x+y)