-2,1,-4,3,-6,( ),-8A.5 B.-5 C.8 D.7 发布时间:2017-12-19 12:58 │ 来源:www.tikuol.com 题型:单项选择题 问题: -2,1,-4,3,-6,( ),-8A.5B.-5C.8D.7
题型:单项选择题 数列{an}的前n项和是Sn,若数列{an}的各项按如下规则排列:12,13,23,14,24,34,15,25,35,45,16,…,若存在整数k,使Sk<10,Sk+1≥10,则ak=______. 查看答案