原式=(a+1)(a-1)/(a+1)^2+(a)/(a-1)*1/a =(a-1)/(a+1)+1/(a-1) =[(a-1)^2+1]/(a^2-1) =[(根号2)^2+1]/(2+1+2根号2-1) =3/(2+2根号2) =3(根号2-1)/2(2-1) =3(根号2-1)/2
