纵观近几年的高考试题中有关数列的考题,不少试题涉及到数列{n.xn-1}求和.对于这种类型的题目,一般采用错位相减法求和.在这里,我们介绍另一种求和方法,即是利用导数求和.这种方法能够简化运算过程,准确地得到结果.注意到当x≠1时,利用等比数列求和公式有1+x+x2+…+xn=xnx+-1-1 Throughout the recent years of college entrance examination questions on the series of test questions, many questions related to the sequence {n.xn-1} summation .For this type of topic, the general use of the disjunction subtraction summation. Here, we introduce Another method of summation is the use of derivative summation, which simplifies the process and produces accurate results. Note that when x ≠ 1, the summation formula using the geometric sequence is 1 + x + x2 + ... + xn = xnx + -1-1