proposition: Lemma Rmult_0_r : forall r, r * 0 = 0.
proof: Proof. intros r; apply (Rplus_eq_reg_l r). rewrite <-(Rmult_1_r r) at 1; rewrite <-Rmult_plus_distr_l. now rewrite 2Rplus_0_r, Rmult_1_r. Qed.
imports: RelationClasses Raxioms Rpow_def ZArith ZArithRing RealField