proposition: Lemma rootCpX n x k : (k > 0)%N -> 0 <= x -> n.-root (x ^+ k) = n.-root x ^+ k.
proof: Proof. by case: n => [|n] k_gt0; [rewrite !root0C expr0n gtn_eqF | apply: rootCX]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)