在有关数列问题中 ,经常要求数列的通项 .许多同学对此类问题常感到困难 .特别是给出Ｓｎ 与ａｎ 的函数关系 ,即Ｓｎ=ｆ(ａｎ)型 ,其中Ｓｎ 表示数列 {ａｎ}的前ｎ项和 ,ａｎ 表示数列的第ｎ项 .此类题难就难在关系复杂 ,不便转化 .下面笔者以一道高考题为例谈一谈此类题的解 Frequently required series of general terms in the relevant series of questions. Many students often find it difficult to deal with such problems. Especially given the functional relationship between Sn and an, that is Sn = f (an) type, where Sn represents the series {an} The first n terms of the first, and an represent the nth term of the sequence. This kind of difficulty is difficult to be complicated and inconvenient. Here the author takes a college entrance examination question as an example to discuss the solution of such a problem.