裂项相消是数列求和的一个重要数学方法.裂项相消法实质上是把数列的通项裂为一个新数列“两项的差”的形式,从而达到数列求和时相邻或相隔的两项间相互抵消而求出和的目的.通过此类题型的考查,可以培养同学们的逆向思维,开发同学们的智力,检查同学们思维的灵活性.近几年的数学高考试题频频用到此法来求数列的前n项和,本文就解决这类 The fission item cancellation is an important mathematical method of summation of the numbers. The fission item elimination method virtually divides the generalization of the sequence into a new sequence and the form of “difference of two terms” Adjacent or separated from each other and find the sum of the sum of the purpose of such questions by examining the students can develop the reverse thinking, develop the intelligence of students, check the students thinking flexibility. Mathematical college entrance examination questions frequently used this method to seek the first n items and columns, this article will solve this type