数列是一种特殊的函数,解数列题时要注意运用函数与方程的思想方法,同时也要注意运用极限的思想、分类讨论的思想、等价转化的思想等数学思想与方法去解题。错误!未找到引用源。等差数列的求和公式是关于n的二次函数,所以解题时可借助二次函数的性质求解。 The sequence is a special kind of function. When solving a series of questions, we should pay attention to the way of thinking of using functions and equations. At the same time, we should also pay attention to using mathematical thinking and methods such as extreme thinking, classified discussion and equivalent transformation to solve problems. Error! Reference source not found. The summation equation of arithmetic sequence is about the quadratic function of n, so solving the problem can be solved by the nature of quadratic function.