proposition: Lemma mul_adj_mx n (A : 'M[R]_n) : \adj A *m A = (\det A)%:M.
proof: Proof. by apply: trmx_inj; rewrite trmx_mul trmx_adj mul_mx_adj det_tr tr_scalar_mx. 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)