求翻译：本文分析了函数极值定义及其存在的必要及充分条件以及导数在经济领域中的应用，其中“边际”和“弹性”是导数在经济分析应用中的两个重要概念，把经济活动中的成本利润问题，用我们所学的数学导数知识进行解答，达到最优化的处理，对很多经营决策起了非常重要的作用，这在经济学领域有着非常重要的意义。是什么意思？

This paper analyzes the extremal function defined and its existence is necessary and sufficient condition for the derivative in the economic sphere, including the "marginal" and "flexibility" is a derivative of two important concepts in the application of economic analysis, economic activities the c

This paper analyzes the function is defined and its value is the necessary and sufficient condition, as well as in derivatives in the field of economics, the application of the "marginal" and "flexibility" is a derivative in the economic analysis of the application of the two important concepts, eco

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This analysis has function extreme defined and exists of necessary and the full conditions and derivative in economic area in the of application, which "marginal" and "elastic" is derivative in economic analysis application in the of two important concept, to economic activities in the of cost profi

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