已知数列{an}是公差不为0的等差数列,a1=2,且a2,a3,a4+1成等比数 发布时间:2017-05-03 10:17 │ 来源:www.tikuol.com 题型:解答题 问题: 已知数列{an}是公差不为0的等差数列,a1=2,且a2,a3,a4+1成等比数列.(Ⅰ)求数列{an}的通项公式;(Ⅱ)设bn=2n•(an+2),求数列{bn}的前n项和Sn.
题型:解答题 He pretended to be a doctor, but ________ he is a cheat.[ ]A. in a word B. in particularC. in practice D. in all 查看答案