x/x-1- x/x+1)除以2x/1-x,
=[x(x+1)/(x-1)(x+1)-x(x-1)/(x+1)(x-1)]*(1-x)/2x
=2x/(x+1)(x-1) *(1-x)/2x
=-1/x+1
x=根号3
原式＝-1/(1+根号3)=(1-根号3)/2