在《二次根式》一章的学习中,规定如果没有特别说明,根号内被开方数都表示非负数。因此对于一些具体问题,要根据题目特点,以二次根式的概念为依据对字母的取值进行,充分挖掘其隐含条件,现举例说明。例1化简-a1.分析:根据二次根式定义,开方数-1a应是非负的,又分母不能为零,所以 In the study of the chapter “Secondary Roots”, it is stipulated that if there is no special explanation, the number of square roots within the root number is non-negative. Therefore, for some specific issues, according to the characteristics of the topic, the value of the letters is taken as the basis of the concept of the secondary roots, and the hidden conditions are fully explored. Example 1 Simplification-a1. Analysis: According to the definition of the secondary root formula, the square root number-1a should be non-negative, and the denominator can not be zero, so