intros.
ring.
Qed.
(** we now generalize the theorem to the nth-root *)
Fixpoint power (x n:nat) {struct n} : nat :=
match n with
O => 1
| (S n) => (x*(power x n))
end.

Lemma power_mult_lemma1 : forall (n x y:nat),(power (x*y) n)=(power x n)*(power y n).
induction n;simpl;trivial.