函数是高中数学的主线,是历年来高考的重中之重,但由于函数内容是学生刚上高中时学习的,受当时学生知识基础的限制,对有关概念认识肤浅,理解不透,对一些相似的问题常常混淆,导致错解.在高三数学总复习时,很有必要对一些易混的问题加以整理辨析.进一步深化认知,提高能力.本文分别举例说明.一、函数的定义域为D与函数在D上有意义 Function is the main line of high school mathematics, is the top priority of the college entrance examination over the years, but because the content of the function is when students first learn in high school, subject to the knowledge base of the students at the time of the understanding of the concept of superficial understanding of impervious, Similar problems are often confused, leading to misunderstanding.In the general review of mathematics in the third year, it is necessary to sort out some of the problems that can be mixed to further deepen the cognition and improve the ability.This paper respectively illustrate.First, the function of the domain is D and function in D meaningful