Question

计算：若x=1/根号2-1，求{（x+1/x平方-x）-（x/x平方-2x+1）}除以1/x的值

Answer 1

{（x+1/x平方-x）-（x/x平方-2x+1）}除以1/x
={(x+1)/[x(x-1)]-x/(x-1)²}*x
=(x+1)/(x-1)-x²/(x-1)²
=(x²-1-x²)/(x-1)²
=-1/(x-1)²
x=1/√2-1=(√2+1)/(√2-1)(√2+1)=√2+1
原式=-1/(√2+1-1)²=-1/2

Answer 2

错了吧，最后一项是x+1吧原式=[(x-1)2/(x+1)(x-1)]×[(x+1)/2(x-1)] =[(x-1)/(x+1)]×[(x+1)/2(x-1)] =1/2 所以x=3,5-2倍根号7，7+π时原式都等于1/2 很不错哦，你可以试下
oс☆nqiюg讧辏zoс☆j※贰rc◇81240218752011-9-13 1:20:13