先化简再求值x/x²-1(x-1/x-2)

来源：学生作业学帮网编辑：学帮网时间：2024/05/27 12:11:03

=x/(x+1)(x-1) ×(x-1-2x)/x
=x/(x+1)(x-1)×[-(x+1)/x]
=-1/(x-1)
=1/(1-x)
当x=2时
原式=1/(1-2)=-1