原式=[1/(a-2)+(a+1)(a-1)/(a+2)(a-1)]÷[a²/(a+2)²]
=[1/(a-2)+(a+1)/(a+2)]÷[a²/(a+2)²]
=(a+2+a²-a-2)/[(a-2)(a+2)]×[(a+2)²/a²]
=a²/[(a-2)(a+2)]×[(a+2)²/a²]
=(a+2)/(a-2)
原式=[1/(a-2)+(a+1)(a-1)/(a+2)(a-1)]÷[a²/(a+2)²]
=[1/(a-2)+(a+1)/(a+2)]÷[a²/(a+2)²]
=(a+2+a²-a-2)/[(a-2)(a+2)]×[(a+2)²/a²]
=a²/[(a-2)(a+2)]×[(a+2)²/a²]
=(a+2)/(a-2)