数列的分类繁多,通项公式的求法也各异,但其中某些方法所涉及的理论问题超出了现行教材的要求和中学生的知识实际,而等差数列与等比数列是中学阶段重点学习的两个典型数列,因而掌握好这两个数列对我们进一步研究其他一般数列有着重要的意义。本文仅讨论在中学教材范围内,如何借助这两个数列来要求某些数列的通项公式的问题。 The classification of numbers is numerous, and the formulas for general term formulas are also different. However, the theoretical problems involved in some of these methods exceed the requirements of the current textbooks and the knowledge of middle school students. The arithmetic arrays and geometric progressions are the focus of secondary school learning. Two typical series, so mastering these two series is of great significance to our further study of other general series. This article only discusses how to use the two series to ask for the general formula of certain series within the scope of the teaching materials of the middle school.