通分：x-1分之x与-x-1

题目

通分：x-1分之x与-x-1
通分：（x-1）分之x与（-x-1）

答案

(x-1)分之x=x/(x-1)
(-x-1)=[(-x-1)(x-1)]/(x-1)
=[-(x+1)(x-1)]/(x-1)
=-(x²-1)/(x-1)
=(1-x²)/(x-1)