x2-y2-2x-2y化简2在x后面的是平方老师的答案为什么是0

问题描述:

x2-y2-2x-2y化简
2在x后面的是平方
老师的答案为什么是0

(x-1)2-(y+1)2
2是平方

x2-y2-2x-2y
=(x+y)(x-y)-2(x+y)
=(x+y)(x-y-2)

x²-y²-2x-2y
=(x+y)(x-y)-2(x+y)
=(x+y)(x-y-2)