原式=(2a²-2+a+1-a+1)/(a+1)(a-1)÷[-(a-a³-a)/(a+1)(a-1)]
=2a²/(a+1)(a-1)×(a+1)(a-1)/a³
=2/a
=2/2
=1第一步有点看不懂，为什么是(2a²-2+a+1-a+1)2(a+1)(a-1)+(a+1)-(a-1)
采纳吧