apply CV_mult.
- intros eps ep; exists 0%nat; rewrite Rdist_eq; intros n _; assumption.
- exact (cv_infty_cv_0 pow_2_n pow_2_n_infty).
Qed.

Lemma IVT_cor :
forall (f:R -> R) (x y:R),
continuity f ->
x <= y -> f x * f y <= 0 -> { z:R | x <= z <= y /\ f z = 0 }.