数列的基本知识和概念在整个高中数学知识中占有十分重要的地位,要想学好这一章的知识,一方面要运用函数的思想帮助理解等差数列和等比数列中项与项数之间的关系,另一方面也要从整体上认识数列中的通项公式a_n与前n项和公式S_n的关系,并借此巧妙解题. The series of basic knowledge and concepts occupies a very important position in the high school mathematics knowledge. In order to learn the knowledge of this chapter, we must use the idea of ​​function to help understand the difference between the number of items in the arithmetic sequence and the geometric sequence. The relationship, on the other hand, must also understand the relationship between the general formula a_n in the sequence and the first n terms and the formula S_n as a whole, and use this to solve the problem.