proposition: Lemma Rmult_inv_r_id_m : forall r1 r2, r1 <> 0 -> r1 * r2 * / r1 = r2.
proof: Proof. now intros r1 r2 r1n0; rewrite (Rmult_comm r1), Rmult_inv_r_id_l. Qed.
imports: RelationClasses Raxioms Rpow_def ZArith ZArithRing RealField