proposition: Lemma roots_opp p : roots (- p) =2 roots p.
proof: Proof. move=> a b; have [->|p0] := eqVneq p 0; first by rewrite oppr0. by apply/roots_eq=> [||x]; rewrite ?oppr_eq0 ?p0 ?rootN. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg poly polydiv ssrnum zmodp) mathcomp(polyorder path interval ssrint)