已知数列(AN)是等差数列,是其前N项的和,求证:S6,S12-S6,S18-12成等差数列.
已知数列{An}是等差数列,Sn是其前n项的和,求证S6,S12-S6,S18-S12也成等差数列.
已知数列{An}是等差数列,Sn是其前n项的和,求证S6, S12-S6,S18-S12也成等差数列. 辛苦, 多谢 在
已知数列{an}是等差数列,Sn是其前几项的和,求证S6,S12-S6,S18-S12也成等差数列
以知数列{An}是等比数列.公比Q不等于1,Sn是其前n项和,a1,a7,a4成等差数列.求证2S3,S6,S12-S6
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
设Sn是等差数列An的前n项和,若S3/S6=1/3,则S6/S12等于
关于等差数列基础题已知Sn是 等比数列An的前n项和,S3,S9,S6成等差数列,求证 A2,A8,A5成等差数列(步骤
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,诺S3/S6=1/3,则S6/S12的值等于
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,诺S3/S6=1/3则S6/S12=多少
已知Sn是等比数列{an}的前n项和,S3,S9,S6成等差数列,求证a2,a8,a5成等差数列.