函数的值域是高中数学的一块重要知识点,也是高考的必考内容.由于它的求解具有灵活多样的特点而成为学生学习的一大难点.进入高三第一轮复习以来,虽然教师把值域求解的各种基本方法都作了系统的讲解,但由于导数法相对其他方法具有简洁实用、适用性广的特点,因此它仍然是很多学生求解的灵丹妙药.的确,运用这一方法求闭区间上函数的值域学生不成问题,但是在求开区间上函数的值域 The value range of the function is an important knowledge point of high school mathematics and also the compulsory part of the college entrance examination.As it has flexible and diverse characteristics, it becomes a major difficulty for students to learn.From the first round of the third year of high school, However, it is still a miracle cure for many students due to its simpleness and practicability and wide applicability compared with other methods. Indeed, the use of this method to find the closed interval The value of the function on the students is not a problem, but the range of functions in the open interval