X²-Y²-X-Y 的值(分解因式)

问题描述:

X²-Y²-X-Y 的值(分解因式)

(x-y)(x+y)-(x+y)
=(x+y)(x-y-1)

(x-y)(x+y-1)

原式=(x+y)(x-y)-(x+y)
=(x+y)(x-y)-(x+y)x1 [可省略]
=(x+y)(x-y-1)