设等比数列an的前n项和为Sn,若a1=1,S6=4S3,求a4及sn
设等比数列{an}的前n项和为Sn,若S6:S3=1:2,则S9:S3=?
设等比数列an的前n项的和为Sn,若S6/S3=3,则S9/S6=
1.设等比数列{an}的前n项和为Sn,若S6/S3=3,则S9/S6=?
设sn是等比数列{an}的前n项和,是s3/s6=1/3.则s6/s12=
设等比数列an的前n项的和为Sn,若S6/S3=1/2,则S9/S3=
(2014•南宁二模)设等比数列{an}的前n项和为Sn,若a1=1,S6=4S3,则a10=______.
设an公差不为0的等差数列.(1)前n项和为Sn,Sn=110,a1.a2.a4为等比数列.求an通项公式.
设{an}是公比不等于1的等比数列,Sn是其前n项和,若a1,2a7,3a4成等差数列,求证12S3,S6,S12-S6
等差数列{an}的前n项和为Sn,设S3=12,且2a1,a2,a3 1成等比数列,求Sn?
等差数列an的前n项和为Sn,设S3=122,且2a1.a2.,a3+1成等比数列,求Sn
记等差数列{an}的前n项和为Sn,设S3=12,且2a1,a2,a3+1成等比数列,求Sn.
设等比数列{an}的前n项和为sn,若S6,S9,S3成等差数列,问2S3,S6,S12-S6S能否成等比数列?请说明理