Exactly what properties of exponentiation are you given to work with?
If you don't know what exponentiation is, you have no hope of proving anything about it. (Not saying you don't know how to exponentiate--just that your book/prof is not expecting you to prove this without giving you something to start from. Look in your chapter or ask your prof what you're allowed to assume about exponentiation to begin with.)
For induction hypothesis, assume , where and are integers.
We begin by .
Multiplying through by a, we obtain .
Plug in the assumption for the left handside in the parethesis, we obtain
. The result is as desired.
Consequently, by induction hypothesis for all integers and .