6. \(\dfrac{a^3+2a^2-a-2}{a^2-1}\)

\(\dfrac{a^2(a+2)-(a+2)}{(a-1)(a+1)}=\dfrac{(a+2)(a-1)(a+1)}{(a-1)(a+1)}=a+2\), при \(a\ne-1,\;a\ne1\).