{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

设Sn为等差数列{An}的前n项和,求证：{Sn/n}是等差数列 已知数列{an}的前n项和sn满足sn=an^2+bn,求证{an}是等差数列 (1)已知数列an的前n项和为sn满足sn=an²+bn,求证an是等差数列(2)已知等差数列an的前n项和为sn,求证数列sn/n也成等差数列 数列的前n项和公式Sn:但只知道Sn,证明an是等差数列 是否存在等比数列{an},其前n项和Sn组成的数列{Sn}是等差数列 已知an是等差数列,前n项和为Sn,求证:S3n=3(S2n-Sn) 设等差数列{an}公差d是2,前n项和为Sn,则lim(an^2-n^2)/Sn 设等差数列{an}公差d是2,前n项和为Sn,则lim(an^2-n^2)/Sn {an}是等差数列,Sn=n2-2n,求：an {an}是等差数列前n项和Sn已知Sm=a Sn-Sn-m=b 求Sn 记数列{an}的前n项和为Sn,若{Sn/an}是公差为d的等差数列,则{an}为等差数列的充要条件是d=? an是等差数列,sn为前N项和,Sm/Sn=m2/n2 则am/an= 已知数列{an}中,a2=2,前n项和为Sn,且Sn=n(an+1)/2证明数列{an+1-an}是等差数列 证明：数列{an}为等差数列的充要条件是{an}前n项和Sn=An^2+Bn 等差数列用n、d、an表示前n项和Sn的公式是? 已知数列{an}的前n项和为Sn=n^2-3n,求证：数列{an}是等差数列 已知数列{an}的前n项和Sn=100n-n^2,证明{an}是等差数列 已知数列｛an｝的前n项和sn=n方+3n,求证数列{an}是等差数列