文献类型：期刊文献

中文题名：一元函数凹凸性的一个充分条件

英文题名：A Sufficient Condition for the Concavity and Convexity of a Function with One Variable

作者：李德奎[1]

第一作者：李德奎

机构：[1]甘肃中医药大学定西校区理科教学部,甘肃定西743000

第一机构：甘肃中医药大学定西校区

年份：2017

卷号：44

期号：2

起止页码：114

中文期刊名：辽宁大学学报（自然科学版）

外文期刊名：Journal of Liaoning University：Natural Sciences Edition

基金：教育部科技研究重点项目(212180);甘肃省自然科学基金项目(1610RJZA080)

语种：中文

中文关键词：一元函数;凹凸性;充分条件

外文关键词：a function with one variable; concavity and convexity; sufficient condition

摘要：研究一元函数凹凸性的一个充分条件.首先给出凹凸函数的定义和图像,把函数图像的拐点分为两类.然后利用函数的三阶导数在二阶导数为零处的正负,判断拐点的类型进而得到函数的凹凸性.最后用一个实例说明所得结论的正确性.
A sufficient condition for the concavity and convexity of a function with one variable is studied in this paper. Firstly, definition and figure for the concavity and convexity of a function is given, inflection points of functional figure are divided into two types. Secondly, inflection point type is judged to obtain the concavity and convexity of a function by using the positive or negative value of three order derivations in point where two order derivations is equal to zero. Finally, a example is given to illustrate correcmess of the conclusion.