proposition: Lemma derivXsubC (a : R) : ('X - a%:P)^`() = 1.
proof: Proof. by rewrite derivB derivX derivC subr0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)