Sn是等差数列前N项和,且S5/S3=9/5 求S9/S5
设Sn是等差数列前n项和 a5/a3=5/9则S9/S5=
设Sn是等差数列{an}的前n项和,若a5/a3=5/9,则S9/S5=:
等差数列an前n项和Sn且6S5-5S3=5,a4等于多少
已知等差数列{an}的前n项和Sn满足S3=0,S5=-5,
设Sn是等差数列{an}的前n项和,若a5/a3=5/9,则S9/S5值为?
设等差数列[an]的前n项和为Sn,若a5=5a3,则S9/S5等于多少?
等比数列的前n项和为Sn,a1为3/2,且S3,S5,S4成等差数列,求an
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
设{an}是公差d≠0的等差数列,Sn是它的前n项和,若a1=4,且S3/3和S4/4的等比中项为S5/5,求{an}的
已知等差数列{an}前n项和为Sn,公差d≠0,且S3+S5=50,a1,a4,a13,成等比数列,求{an}通项公式.
已知等差数列{an}的前n项和伟sn,公差d≠0,且s3+s5=50,a1,a4,a13城等比数列.求数
已知等差数列{an}前n项和为Sn,公差d≠0,且S3+S5=50,a1,a4,a13,成等比数列 设{bn/an}是首