数列问题是高中数学的重要内容,是学习高中数学的重点、难点,也是历届高考必考的内容。数列问题中常见的错解有以下几类:一忽略了项数n的限定条件致错例题:已知数列{an}的前n项和sn=2n2-3n+1,求an的通项公式。错解:当n=1时,a1=s1=0;当n≥2时,an=Sn-Sn-1=(2n2-3n+1)-[2(n-1)2-3(n-1)+1]=4n-5。∴an=4 n-5。错解分析:由an=Sn-Sn-1求得an是n从2开始的自 Number sequence is an important part of high school mathematics, high school mathematics is to learn the key and difficult, but also the previous college entrance examination must be content. Misunderstandings in the series of problems are the following categories: A neglected number of qualified conditions n result in wrong example: the first n series of known sequence {an} and sn = 2n2-3n + 1, find an general formula . Misalignment: a1 = s1 = 0 when n = 1; an = Sn-Sn- 1 = (2n2-3n + 1) - [2 1) +1] = 4n-5. ∴an = 4 n-5. Decomposition analysis: An = Sn-Sn-1 An is n from 2 to start from