proposition: Lemma divpZl c p q : (c *: p) %/ q = c *: (p %/ q).
proof: Proof. have [-> | qn0] := eqVneq q 0; first by rewrite !divp0 scaler0. by apply: IdomainUnit.divpZl; rewrite unitfE lead_coef_eq0. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop ssralg poly)