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In calculus, the product rule is a formula used to find the derivatives of products of two or more functions. It may be stated as : or in the Leibniz notation :. In differentials notation, this can be written as :. In Leibniz notation, the derivative of the product of three functions (not to be confused with Euler's triple product rule) is :. == Discovery == Discovery of this rule is credited to Gottfried Leibniz, who demonstrated it using differentials. (However, Child (2008) argues that it is due to Isaac Barrow). Here is Leibniz's argument: Let ''u''(''x'') and ''v''(''x'') be two differentiable functions of ''x''. Then the differential of ''uv'' is : Since the term ''du''·''dv'' is "negligible" (compared to ''du'' and ''dv''), Leibniz concluded that : and this is indeed the differential form of the product rule. If we divide through by the differential ''dx'', we obtain : which can also be written in Lagrange's notation as : 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「product rule」の詳細全文を読む スポンサード リンク
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