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(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
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(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
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Local Open Scope R_scope.

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Lemma derive_pt_sqrt :
forall (x:R) (pr:0 < x),
derive_pt sqrt x (derivable_pt_sqrt _ pr) = / (2 * sqrt x).