设Sn是等差数列的前n项和,S3:S6=1:3,则S6:S9=

设Sn是等差数列an的前n项和,若S3/S6=1/3,则S6/S7=? 设Sn是等差数列(An)的前n项和,若S3/S6=1/3,求S6/S12=? 设Sn是等差数列{An}的前n项和,若S3/S6=1/3,则S6/S12=? 设Sn是等差数列的前n项和,S3:S6=1:3,则S6:S9= 设Sn是等差数列{an}的前n项和,若S3/S6=1/3,则S6/S12=? 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S3/S6=1/3,求S6/S12 1.设Sn是等差数列【An]的前n项和,若S3/S6=1/3,求S6/S12 设Sn是等差数列{an}的前n项和,若S3/S6=1/4,则S6/S12等于? 设Sn是等差数列an的前n项和,若S3/S7=1/3,则S6/S7= 设Sn是等差数列an的前n项和,s6/s12=3/10,则s3/s9=¿ 设Sn是等比数列{an}的前n项和,S3,S9,S6,成等差数列,则公比q=? 设等差数列{an}的前n项和为Sn,若S6/S3=3,则S9/S6=? 设Sn是等比数列的前n项和,S3,S9,S6成等差数列 求证a2,a8,a5成等差数列 等差数列(an)的前n项和sn,若s6：s3=3,求s9：s6 设Sn是等差数列an前n项和 若S3/S6=1/3则S6/S12正确的做法我知道 但我这种做法怎么错了Sn成等差 所以S3,S6-S3,S12-S6也成等差因为S3/S6=1/3,所以S6-S3=2S3,所以S12-S6=3S3所以S12=6S3 所以S6/S12=1/2 设Sn是等差数列｛an｝的前N项和,诺S3/S6=1/3则S6/S12=多少 设Sn是等差数列{an}的前n项和,若S3/S6=1/3,则S6/S12等于——