数列求和是高考数学的重点内容,主要包括等差、等比数列求和及一些特殊的非等差、等比数列求和。特殊数列求和问题一般都是转化为等差、等比数列的求和问题。下面例谈数列的前n项和求解的几种常用方法。 The summation of series is the key content of college entrance examination math, which mainly includes the arithmetic of sum of difference, geometric series and some special non-arithmetic and sum of geometric series. Special series of summation problems are generally converted into equal-difference, geometric ratio of the summation of the problem. The following example talk about the first n items of the series and several commonly used methods to solve.