a方+2a+1分之a方-1-a方分之a方+2a
=a²/(a+1)²+a(a+1)/(a²-1)
=a²/(a+1)²+a(a+1)/(a+1)(a-1)
=a²(a+1)²+a/(a-1)
=[a²(a-1)+a]/(a+1)²(a-1)
=(a³-a²+a)/(a+1)²(a-1)
a方+2a+1分之a方-1-a方分之a方+2a
=a²/(a+1)²+a(a+1)/(a²-1)
=a²/(a+1)²+a(a+1)/(a+1)(a-1)
=a²(a+1)²+a/(a-1)
=[a²(a-1)+a]/(a+1)²(a-1)
=(a³-a²+a)/(a+1)²(a-1)