proposition: Lemma ex_derive_n_scal_r (f : R -> R) (n : nat) (a x : R) : ex_derive_n f n x -> ex_derive_n (fun y => f y * a) n x.
proof: Proof. move/(ex_derive_n_scal_l _ _ a). apply ex_derive_n_ext => y ; ring. Qed.
imports: Coq(Reals Psatz ssreflect) Rcomplements Rbar Lim_seq Iter Hierarchy Continuity Equiv