intros e n; elim n; simpl in |- *; auto with real.
intros n0 H' m; rewrite H'; auto with real.
Qed.
Hint Resolve pow_O pow_1 pow_NR0 pow_add: real.

Theorem pow_RN_plus :
forall (e : R) (n m : nat),
e <> 0%R -> (e ^ n)%R = (e ^ (n + m) * / e ^ m)%R.