induction n1; intuition; simpl in *.
symmetry.
eapply ratMult_1_l.
rewrite IHn1.
rewrite ratMult_assoc.
intuition.
Qed.

Lemma expRat_base_prod : forall n r1 r2,
expRat (r1 * r2) n == (expRat r1 n) * (expRat r2 n).