等差数列an的前n项和为Sn,lim(Sn/n^2)=-a1/9＜0,求n为何值时.sn最大

{an}是等差数列,a1不等于0,Sn是它前n项的和.求lim (n→∞) (Sn+S(n+1))/(Sn+S(n-1)) 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 等差数列{an} 前n项和为sn,则lim（n趋向无穷）【sn/（an^2）】=? 等差数列an的前n项和为Sn,lim(Sn/n^2)=-a1/9＜0,求n为何值时.sn最大 设Sn为等差数列an的前n项和.求证Sn/n为等差数列 极限的简单运算2设等差数列an的公差为2,前n项和为Sn,则lim ((an^2-n^2)/Sn)=? 设等差数列an的公差d为2,前n项和为Sn,则lim(an^2-n^2)/Sn=? 等差数列列｛an｝的前n项和为Sn,公差为2,则lim(n→∞)Sn/an^2=? 等差数列{an}的前n项和为Sn,公差为2,则lim（n到无穷大）Sn/ an^2= 等差数列{an}的前n项和为sn,a10 设Sn为等差数列{An}的前n项和,求证：{Sn/n}是等差数列 设等差数列的公差d为2,前n项和为Sn,则lim(n→∞)(an^2-n^2)/Sn 已知数列an是等差数列,且a1≠0,Sn为这个数列的前n项和.求1、lim nan/Sn 2、lim (Sn+Sn+1)/(Sn+Sn-1) 已知数列{an}是首项为1,公差为2的等差数列,Sn(n属于N)是数列的前n项和,则lim下面为n到无穷 Sn/n^2减1...已知数列{an}是首项为1,公差为2的等差数列,Sn(n属于N)是数列的前n项和,则lim下面为n到无穷 Sn/ Sn为等差数列an的前n项和S'n为等差数列Sn为等差数列{an}的前n项和S‘n为等差数列{bn}de前n项和,已知Sn:S’n=（7n+1）:（4n+27）,求a11:b11的值 设等比数列an的公比为q,前n项和为sn,若s(n+1),sn,s(n+2)成等差数列,求q的值 设等比数列[an]的公比为q,前n项和为Sn,若S(n+1),Sn,S(n+2)成等差数列,则q的值?