1/x+1-1/x²-1×x²-2x+1/x+1,其中x=根号2-1

1/x+1-1/x²-1×x²-2x+1/x+1,其中x=根号2-1

1/(x+1)-1/(x²-1)×(x²-2x+1)/(x+1),其中x=根号2-1
=1/(x+1)-1/[(x-1)(x+1)]×(x-1)²/(x+1)
=1/(x+1)-(x-1)/(x+1)²
=(x+1-x+1)/(x+1)²
=2/(x+1)²
=2/(√2-1+1)²
=2/(√2)²
=2/2
=1

答案等于一

要知道，我比上面那厮快。