对由递推公式给出的数列,寻求通项公式,一些刊物介绍了很好的方法。本文试谈利用等差、等比数列的知识和已学过的数学方法,求这类数列通项公式,这些对中学生是易于接受的。 一、用不完全归纳法找通项 由递推公式给出的数列,一般用不完全归纳法求通项。即由递推公式算出前有限项(有时算出结果,有时写出表达式)归纳得通项,再用数学归纳法予以证明。 For the series given by the recursive formula, the general term formula is sought, and some publications introduce good methods. This article tries to use the knowledge of equal, odd, and mathematical mathematics to find such general equations of numbers, which are easy to accept for middle school students. First, find the general term by incomplete induction method. The series given by the recursive formula generally uses the incomplete induction method to find the general term. That is, the recursive formula is used to calculate the first finite term (sometimes calculating the result, and sometimes writing the expression) to general term, and then to prove it by mathematical induction.