(a-3分之1-a²-1分之a+1)×(a-3)
=(a-3)/(a-3)-(a+1)(a-3)/(a+1)(a-1)
=1-(a-3)/(a-1)
=(a-1-a+3)/(a-1)
=2/(a-1)
=2/(√2+1-1)
=2/√2
=√2