proposition: Lemma cofactorZ n a (A : 'M[R]_n) i j : cofactor (a *: A) i j = a ^+ n.-1 * cofactor A i j.
proof: Proof. by rewrite {1}/cofactor !linearZ detZ mulrCA mulrA. 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)