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导数在函数中的应用是现今高考的一大热点问题,年年必考,在这道压轴的大题中,解答时常涉及构造函数,我简单谈一下常用的构造方法.一、作差法(直接构造法)这是最常用的一种方法,通常题目中以不等式形式给出,我们可以作差构造新的函数,通过研究新函数的性质从而得出结论.当然,适合用这个方法解的题目中,构造的函数要易于求导,易于判断导数的正负.
Derivative function in the application of the entrance exam is now a major hot issue, year after year will be required to test, in this big problem of the finale, the answer often involves constructor, I briefly talk about commonly used method of construction. Direct construction method) This is the most commonly used method, usually given in the form of inequalities, we can make a difference function of the new function, by studying the nature of the new function to draw conclusions.Of course, suitable for this method of solution In the title, the constructed function should be easy to find the derivative, easy to judge the positive and negative of the derivative.