化简：（x-y)²-1/x-y-1 =.

化简：（x-y)²-1/x-y-1 =.

(x-y-1)(x-y+1)/(x-y-1)=x-y+1
平方差公式啊
a^2-b^2=(a+b)(a-b)
(x-y)^2看成a 1看成b

x-y+1

原式=[(x-y)²-1²]/(x-y-1)
=(x-y+1)(x-y-1)/(x-y-1)
=x-y+1
平方差公式：a²-b²=(a+b)(a-b)
即(x-y)²-1²=(x-y+1)(x-y-1)