解答数学题需要选择一个突破口,并以此为解题的切入点,由点及面,逐步解决问题．这需要分析题目的已知条件和所求问题特征,正确寻找两者之间的隐含关系作为解题的切入点．一、利用常见的等量关系式寻找已知条件与所求问题之间的隐含关系例1若数列{a_n}的前n项和S_n=n~2a_n,且a_1≠0,则(a_n)/(a_(n+1))等于( )． To solve a math problem, you need to choose a breakthrough point, and use this as the starting point for problem solving. From point to area, solve problems step by step. This requires analyzing the known conditions of the topic and the characteristics of the problem to be solved, and correctly finding the implicit relationship between the two as the starting point for solving the problem. First, the use of common isometric relationship to find the implicit relationship between known conditions and the problem of the case Example 1 If the first n and S_n = n~2a_n of the sequence {a_n}, and a_1 ≠ 0, then (a_n) /(a_(n+1)) is equal to ().