定义是研究问题的基础,是揭示概念内涵的逻辑方法,定义本身就是十分本质的方法,是高考考查的热点问题,在历年高考试题中均有涉及.2013年的高考卷,各地不约而同地考查了以等差等比数列定义立意的问题.下面举例说明.一、利用等差数列定义等差数列的典型定义是:一个数列如果从第二项起,每一项与它的前一项的差等于同一个常数的数列称作等差数列.用符号语言描述就是:数列{a n}对任意n∈N*,有a n+1-a n=d(常数),则{a}是等差数列.一组等价定义的图式是:数列 Definition is the basis of the research problem and the logical method of revealing the connotation of the concept. The definition itself is a very essential method, which is a hot issue of college entrance examination examination, which has been covered in college entrance examination papers over the years. The definition of concentricity isomerism problem.Examples: First, the use of arithmetic sequence definition of arithmetic sequence is a typical definition of a series if the second from the second, with each of its previous difference A series of numbers equal to the same constant is called an arithmetic sequence, which is described by the symbolic language: the sequence {an} has an n + 1-an = d (constant) for any n∈N *, then {a} The set of equivalent definitions is: Sequence