x^-2x／x^-1÷｛（2x-1／x+1）-x+1｝.其中x=（根号2）＋1
问题描述：
x^-2x／x^-1÷｛（2x-1／x+1）-x+1｝.其中x=（根号2）＋1
答
原式=(x^-2x)/(x+1)(x-1)÷[(2x-1-x^+1)/(x+1)]
=(x^-2x)/(x+1)(x-1)÷[-(x^-2x)/(x+1)]
=-(x^-2x)/(x+1)(x-1)×(x+1)/(x^-2x)
=1/(x-1)
=1/(√2+1-1)
=√2/2