x2-x-y2-y 解法:=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1)后半部的解法(x+y)(x-y)-(x+y) =(x+y)(x-y-1)怎么得的

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x2-x-y2-y 解法:=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1)后半部的解法(x+y)(x-y)-(x+y) =(x+y)(x-y-1)怎么得的

x2-x-y2-y 解法:=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1)后半部的解法(x+y)(x-y)-(x+y) =(x+y)(x-y-1)怎么得的
x2-x-y2-y 解法:=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1)
后半部的解法(x+y)(x-y)-(x+y) =(x+y)(x-y-1)怎么得的

x2-x-y2-y 解法:=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1)后半部的解法(x+y)(x-y)-(x+y) =(x+y)(x-y-1)怎么得的
哥!你那个是x方y方吧!
有这么个公式 x方-y方=(x+y)(x-y)
所以得到了(x+y)(x-y)-(x+y)
这时候提取公因式(x+y)就得到了(x+y)(x-y-1)

提出(x+y),得(x+y)(x-y)-(x+y) =(x+y)(x-y-1)

(x+y)(x-y)-(x+y)这个式子提取(x+y)后,减号左边得到的是(x-y)。右边是1。结果就是(x+y)(x-y-1)

把 (x+y)看做整体提取公因式
(x+y)(x-y)-(x+y)
=(x+y)(x-y)-(x+y)×1
=(x+y)(x-y-1)