二次根式的条件求值问题,解答方法不易掌握,许多学生视为畏途。本文举例分析其解题思路,归纳方法技巧,供参考。一、定义法依根式定义确定字母取值范围。 The secondary root conditional evaluation problem is difficult to master because of the solution method. Many students regard it as a fearful way. This article analyzes the problem-solving ideas, sums up the methods and techniques for reference. First, the definition method determines the range of letter values ​​according to the root definition.