原式=根号3 - 根号2+（根号2 - 1）/(根号2+1)(根号2 - 1) - 2(根号3 - 1)/(根号3+1)(根号3 - 1)
=根号3 - 根号2 +根号2-1/1-(根号3 - 1)
=根号3 - 根号2 +根号2 - 1 - 根号3+1
=0