已知Sn是等差数列{an}的前几项和,若S3=6,a3=8,则S12-S9的值是
已知Sn是等比数列{An}的前N项和,S3,S9,S6成等差数列,则
设Sn是等差数列An的前n项和,若S3/S6=1/3,则S6/S12等于
设Sn是等差数列{an}的前n项和,若a5/a3=5/9,则S9/S5=:
帮我解2道 数列1 设Sn是等差数列{An}的前项n和,若S3/S5 = 1/3 , 则 S6/ S12 ?2 等差数列
设等差数列{an}的前n项和为Sn 已知S3=S12 则当公差d
设Sn是等差数列{an}的前n项和,若S3/S6=1/3,则S6/S12等于——
设等差数列{an}的前n项和sn,已知a3=12,s12>0.s13
等差数列{an}的前n项和Sn已知a3=12,S12>0,S13
设Sn是等差数列{an}的前n项和,若a5/a3=5/9,则S9/S5值为?
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
已知数列{An}是等差数列前n项和Sn,A3=6,S3=12.
已知等比数列{an}的公比为q,前n项的和为Sn,且S3,S9,S6成等差数列.则q3的值是( )