等比数列an的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1等于1,则S4为多少?

等比数列an的前n项和为sn.且sn的极限=1/2.求a1范围 设数列{an}中,a1=1且an+1=3an+4,求证{an+2}是等比数列求{an}的前n项和为Sn 设数列{an}的前n项和为Sn,且an不等于0,S1,S2,S3 Sn成等比数列,试问a1,a2,a2是等比数列吗 等比数列的前n项和为Sn,a1为3/2,且S3,S5,S4成等差数列,求an 等比数列an的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1等于1,则S4为多少? 已知{an}的前n项和为Sn,且an+Sn=4求证：数列{an}是等比数列 设等比数列{an}的前n项和为Sn,Sn=[a1*（3^n-1）]/2,≥1,且a4=54,则a1=? 设等比数列{an}的前n项和为Sn,已知a1=2011,且an+2an+1+an+2=0(N∈N*),则S2012? 设正项等比数列{An}的首项a1=1/2,前n项和为Sn,且2*10S30 等比数列{an}的前n项和为sn,且4a1,2a2,a3成等差数列.若a1=1,则s4=? 等比数列｛An｝的前n项和为Sn且4a1 2a2 a3成等差数列若a1=1则S4=? 等比数列{an}的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1=1,则S4等于多少? 等比数列（an)的前n项和为Sn ,且4a1,2a2,a3成为等差数列.若a1=1,则S4= 等比数列{an}的前n项和为Sn,且4a1,2a3,a3成等差数列,若a1=1,则S4=?思路,本人基础不好 等比数列｛an｝的前n项和为Sn,且4a1,2a2,a3成等差数列,若a1=1,则S4等于多少 等比数列{An}的前n项和为Sn,且4A1,2A2,A3成等差数列,若A1=1,求S4. 等比数列的一道题.已知等比数列｛an｝的前n项和为Sn,且S3＝7a1,则数列｛an｝的公比q的值为? 高中数列{An}前n项和Sn且A1=0 ,S(n+1)=4An+2.求证{A（n+1）-2An}为等比数列.