proposition: Lemma scalemxDr x A B : x *m: (A + B) = x *m: A + x *m: B.
proof: Proof. by apply/matrixP=> i j; rewrite !mxE mulrDr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)