绝对值历来是教学中的一个难点。学生运用这个概念解题时,常常会产生两个问题:一是,对于绝对值号内的数不加讨论直接得结果。例如,|1-4x|=1-4x;|lg5-1|=lg5-1等等;二是,化简计算含有若干个绝对值的式子时,为什么要分区间讨论。在各个区间内各个绝对值如何取值。 为了突破这一难点,我们曾试用了零点分区直观法进行教学。现将此法介绍如下。 Absolute value has always been a difficulty in teaching. When students use this concept to solve problems, they often have two problems: First, they do not discuss the results directly within the absolute number. For example, |1-4x|=1-4x;|lg5-1|=lg5-1, etc.; Second, when simplifying the calculation of an equation containing several absolute values, why do you want to discuss between partitions? How to determine the absolute value of each interval. In order to break through this difficulty, we have tried a zero-point partitioning method to teach. This law is introduced as follows.