a²-1/a-1×根号（a²-2a+1）/a²-a,
=(a+1)*|a-1|/[a(a-1)]
a>1 时=1+1/a
a<1时-1-1/a
a=1/根号3（分开）+2>1
所以原式=1+1/a=(1+3*根号3)/(1+2*根号3)