proposition: Lemma adjZ n a (A : 'M[R]_n) : \adj (a *: A) = a^+n.-1 *: \adj A.
proof: Proof. by apply/matrixP=> i j; rewrite !mxE cofactorZ. 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)