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

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 设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5= 等差数列an前n项和为Sn,且6Sn-5S3=5,a4=错了，是6S5-5S3=5，求a4 Sn是等差数列前N项和,S3=S9,那么S5=S几 等差数列{an}的前n项和为Sn,且6S5-5S3=5,则a4= 等差数列{an}的前n项和为Sn,且6S5-5S3=5,则a4= 等差数列｛an}前n 项和为Sn ,且6S5-5S3=5 则a4=? 等差数列{an}的前n项和为Sn,且6S5-5S3=5,则a4=______. 等差数列{an}的前n项和为Sn,且6S5-5S3=5,则a4= 等差数列an前n项和Sn且6S5-5S3=5,a4等于多少 等差数列的前n项和为Sn,S3=5,S5=3,求S8 等差数列前n项和sn.a2:a5=5：2.则s3:s5=? {an]是等差数列,sn是是{an]前n项的和,且a1,a3,a4是等比数列,则（S3-S2）/（S5-S3）等于如题 已知{an}是等差数列,且{sn}是{an}的前n项和,a1,a3,a4成等比数列,求(s3-s2)/(s5-s3)的值快 已知{an}是等差数列,且{sn}是{an}的前n项和,a1,a3,a4成等比数列,求(s3-s2)/(s5-s3）的值 等差数列{an}的前n项和为Sn,bn=1/Sn,且a3b3=1/2,S3+S5=21求数列{an}通项公式. 设等差数列{an}的前n项和为Sn,bn=1/Sn,且a3b3=1/2,S5+S3=21,求bn的值 等差数列an的前n项和胃Sn,bn=1/Sn,且a3b3=1/2,S3+S5=21.求证b1+b2+b3...+bn