Sn是等差数列前N项和,S3=S9,那么S5=S几

Sn是等差数列前N项和,S3=S9,那么S5=S几 Sn是等差数列前N项和,且S5/S3=9/5 求S9/S5SORRY.说错了.是Sn是等差数列前N项和,且S5/S3=5/9 求S9/S5 等差数列的前n项和为Sn,若S3=S6,则S9=? 等差数列{ an}的前n项和Sn,S3=S6,则S9=? 等差数列(an)的前n项和sn,若s6：s3=3,求s9：s6 已知等差数列前n项和为Sn,S6/S3=3 求S9除S6 设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5= 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,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 已知Sn为等差数列an前n项和,若S9/S3=3,则a9/a3=? 等差数列an的前n项和为sn若s6/S3=3,则s9/S6=? 设等差数列{an}的前n项和为Sn,若S6/S3=3,则S9/S6=? Sn是等比数列an的前n项和,S3,S9,S6成等差数列,且a2+a5=2am,则m=? Sn是等差数列{an}的前n项和,S7=3(a3+a7),那么S9/a4=? 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!） 设sn是等差数列{an}的前n项和, 若a5：a7=2：3,求s9:(s13-s9)