先化简后求值已知x=根号2+1求x+1-x的平方/x-1的值

x+1-x²/(x-1)
=(x²-1-x²)/(x²-1)
=1/(x²-1)
=1/(2+2根号下2)
=（根号下2-1)/2能详细点吗第一步我都不知道你怎么得到的sorry上面算错了 看不懂继续问。(x+1)-x²/(x-1)=(x+1)(x-1)/(x-1)-x²/(x-1)=(x²-1-x²)/(x-1)=-1/(x-1)=-1/(根号下2+1-1)=-1/根号下2=-根号下2/2