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...