题目是不是x^3/(x-1)-x^2-x-1?
如果是,由整体通分可得,
原式=[x^3-x^2(x-1)-x(x-1)-(x-1)]/(x-1)
=(x^3-x^3+x^2-x^2+x-x+1)/(x-1)
=1/(x-1)