设公差为d的等差数列｛an｝的前n项和为sn,若a1=1,-2/17＜d＜-1/9,则当sn取得最大值时,n为

设公差为d的等差数列{an}的前n项和为Sn,若a1=1,-2/17 谢谢）在等差数列{an}中,设公差为d,若前n项和Sn=-n²;,则{an}的通项公式和公差分别 设Sn为等差数列{an}的前n项和,S5=10,S10=-5,则公差d=? 设等差数列{an}的前n项和为Sn 已知S3=S12 则当公差d 在公差为d的等差数列｛an｝的前n项和为S,若x1 设等差数列{an}的公差为d,若它的前n项和Sn=-n^2,则an=-2n+1,d=-2 设数列{an}的前n项和为Sn,若{an}和{根号sn+n}都是公差为d的等差数列,则a1= 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=? 设等差数列{an}的公差为d,如果前n项和Sn=-n^2,那么an=?,d=? 等差数列{an}的前n项和为Sn,公差d 设{An}为等差数列公差为d,{Bn}为等比数列公比为q,{AnBn}的前n项和Sn为多少? 设{an}是公差d=3的等差数列,an=11,前n项和为14,求n和a3? 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 设等差数列an的公差为d不等于0,前n项和为Sn.则Sn为递增数列的充分必要条件是 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=? 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 设Sn为等差数列{An}的前n项和,若S5=20 S10=-35则公差为