当我们研究的问题包含有多种可能并难以同时处理时,往往需要按所有可能出现的情况分类讨论,得到各种情况的相应结论,这就是分类讨论.分类讨论思想是一种重要的数学思想方法.解题时,正确地分类可使我们抓住问题的本质,有助于我们将复杂问题化为几个较为简单的问题,还有助于培养 When the problems we study contain multiple possibilities and it is difficult to deal with them at the same time, it is often necessary to classify the discussions according to all possible situations and obtain the corresponding conclusions of various situations. This is classified discussion. Classification discussion is an important mathematical idea. Methods. The correct classification when solving a problem allows us to grasp the nature of the problem, help us turn complex issues into simpler problems, and also help develop