问题 解答题 (x-xx+1)÷(1+1x2-1),其中x=3-1 答案 (x-xx+1)÷(1+1x2-1)=x2+x-xx+1÷x2-1+1x2-1=x2x+1×(x+1)(x-1)x2=x-1把x=3-1代入得:原式=x-1=3-1-1=3-2.