近年来,为加强对考生全面思维能力的考查,“分类讨论”的题型在各地中考题中频繁出现。当研究的对象不宜用同一种方法处理或同一种形式叙述时,常要按一定标准把它划分为若干不同情况,再对每种情况逐一求解。这种方法就是“分类讨论”。初中数学中常见的有:按数分类(如绝对值的概念、实数的分类等);按字母取值范围的分类(如二 In recent years, in order to strengthen the examination of candidates’ comprehensive thinking ability, the questions of “category discussion” have frequently appeared in the examination questions in various places. When the object of the study is not suitable to be treated in the same way or in the same form, it is often divided into a number of different situations according to certain criteria, and then each case is solved one by one. This method is “classification discussion.” Commonly used in junior high school mathematics are: classification by number (such as the concept of absolute values, the classification of real numbers, etc.); the classification of ranges by letter (for example, two