a=1/(2+√3)=2-√3
1-2a+a²/a-1 -√a²-2a+1/a²-a
=(a-1)²/a-1 -√(a-1)²/[a(a-1)]
=(a-1)+(a-1)/[a(a-1)]
=a-1+1/a
=2-√3-1+（2+√3)
=3