化简：x平方+x / x-1 除以x平方-1 / x平方-2x+1-（2x-1）

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