等差数列{an}的前n项和为sn=-3/2n^2+205/2n 求数列{|an|}的前n项和Tn

设Sn为等差数列an的前n项和.求证Sn/n为等差数列 等差数列{an}前n项和为Sn=3n-2n^2,求an 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{an}的前n项和为Sn 若a1=Sn> 等差数列{an}的前n项和为Sn,且S10-S5=3,S15=? 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=3n²-2n,证明数列{An}为等差数列 等差数列{an}中an=63-3n,前n项和Sn取得最大值时n的值为 (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 已知an是等差数列,前n项和为Sn,求证:S3n=3(S2n-Sn) 已知等差数列an中,前n项和sn=n^2-15n,则使sn为最小值的n 等差数列{an}的前n项和为sn=-3/2n^2+205/2n 求数列{|an|}的前n项和Tn 等差数列an的前n项和为Sn,已知a5=11 a8=5求an和Sn 等差数列{an},{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1,求an/bn的表达式 等差数列An,Bn的前n项合分别为Sn和Tn,若Sn/Tn=2n/3n+1,求An/Bn的表达式. 已知两个等差数列{an},{bn}的前n项的和分别为Sn,Tn.若Sn/Tn=(5n+3)/(2n-1).求an/bn 等差数列{an},{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1 ,则an/bn=