排列组合是重要的数学方法之一,学生在学习时,往往会感到困难,究其原因是因为排列组合的题型较多,不易分门归类。且解题思路较为独特,与旧知识似乎联系不大,为此介绍几种转换命题的方法,常常能使问题化难为易。一、被上顺序,换成熟悉件翻开课本,从组合数公式的推导过程,可以看到:把组合问题补上顺序后可转换成排列问题,这种补上顺序后,把原设问题转换成熟悉事件的方法。就叫做 Arranging and combining is one of the important mathematical methods. Students often feel difficult when they study. The reason is because the types of questions that are arranged and combined are more difficult to classify. And the problem-solving ideas are more unique and seem to have little connection with the old knowledge. To this end, several methods for transforming propositions are introduced, which often make it difficult to solve problems. First, by the order, replaced by familiar parts to open the textbook, from the derivation process of the formula of the number of combinations, you can see: After the order of the combination of problems can be converted into the arrangement of problems, after the order of the replacement, the original set of problems Convert to a familiar event method. Just called