数列知识历年来都是高考的重点,而且近几年高考对数列考查的分值有增加的趋势。数列综合题常以两类形式出现:交叉数列与子数列。不少同学解答此类问题时感到困难,下面结合实例谈谈这两类问题的命题形式与求解方法。一、交叉数列所谓交叉数列就是一个数列各项分别是由两个或多个数列交叉构成,或者两个或多个数列分别是由交叉条件给出。1.一个数列的各项分别由几个数列交叉构成, Number of columns of knowledge over the years are the focus of college entrance examination, and college entrance examination in recent years on the scores of scores increased trend. Series synthesis questions often appear in two forms: cross and sub-series. Many students feel difficult to answer such questions, the following examples to talk about the two types of questions propositions and solutions. First, the number of crosses The so-called number of crosses is a number of columns Each is composed of two or more series intersect, or two or more series are given by the intersection conditions. 1. A number of the various series of several cross-form,