二次根式概念包含两个知识点: 1 式子a~(1/2)当a≥0时,叫做二次根式; 2 当a≥0时,a~(1/2)≥0,即a~(1/2)是一个非负数。 对于第二个知识点,课本没有配备这相应的习题,人们在教学中通常不够重视,然而这又是考试命题的一个热点。为突出这个知识点,笔者在教学过程中,作了如下努力: The concept of quadratic root contains two points of knowledge: 1 The formula a~(1/2) is called quadratic when a≥0; 2 When a≥0, a~(1/2)≥0, that is, a ~(1/2) is a non-negative number. For the second point of knowledge, textbooks are not equipped with the corresponding exercises. People usually do not pay enough attention in teaching. However, this is a hot topic in the examination proposition. To highlight this knowledge, the author made the following efforts in the teaching process: