数列是高中数学学习的重点和难点,也是近几年来高考数学的一个重要考点.通过对高中阶段数列知识点和高考试题的梳理分析,发现有这样一类数列问题:已知数列的递推式和某一项(通常不是首项),通过数列间的递推关系,求解出该数列的首项或该项前的一些项.对于此类问题,在实际的解题操作中,如 The sequence is an important and difficult point in high school mathematics learning, and also an important test point of mathematics in college entrance examination in recent years.Through combing and analyzing the high school mathematics knowledge and college entrance examination questions, we find that there are such a series of questions: Recursion of known series And a (usually not the first), through the sequence of recursion relations, solve the first of the series or some of the items before. For such problems, the actual problem-solving operations, such as