Question

化简求值(2+1/a-1-1/a+1)÷ (a-a/1-a^2)其中a=2

详细过程！

Answer 1

原式={[2(a²-1)+(a+1)-(a-1)]/(a+1)(a-1)}÷{[a(a²-1)+a]/(a+1)(a-1)}
=[(2a²-2+a+1-a+1)/(a+1)(a-1)]×[(a+1)(a-1)/(a³-a+a)]
=[2a²/(a+1)(a-1)]×[(a+1)(a-1)/a³]
=2/a
=2/2
=1

Answer 2

解 原式=[(3a+3)/(a-1)(a+1)-(a-1)/(a-1)(a+1)]÷[a(1-a^2)-a/(1-a^2)]
=(2a+4)/(a^2-1)×-（1-a^2)/a^3
=(2a+4)/(a^2-1)×(a^2-1)/a^3
=[2(a+2)]/a^3
将a=2代入上式得
原式=[2(2+2)]/2^3
=8/8
=1