等差数列{an}的前n项和为Sn,且a8+a16=0,则有：A.S8

已知等差数列an的前n项和为Sn,且a1^2+a8^2 设等差数列{an}的前n项和为Sn ,且S15>0,a8+a90,a8+a9 数列,等差数列an 的前n项为Sn 且 (a1)^2+(a8)^2 已知等差数列an的前n项和为Sn,a3+a8=13且S7=35,求a7 等差数列{an}的前n项和为Sn,且a8+a16=0,则有：A.S8 已知等差数列an,bn的前n项和为Sn和Tn且Sn/Tn=(4n-5)/(7n+1),则a8/b8= 等差数列｛an｝的前n项和为sn,若S15=90,则a8= 等差数列{an},{bn},的前n项和分别为Sn,Tn且Sn/Tn=(3n-1)/(2n+3)则a8/b8=快. 等差数列（an）,（bn）的前n项和为Sn,Tn,且Sn/Tn=2n/3n+1,则a8/b8=? 等差数列an的前n项和为Sn,已知a5=11 a8=5求an和Sn 设等差数列{an}满足3a8=5a13,且a1>0,Sn为其前n项和,则Sn中最大的是前几项和? 在等差数列{an}中,已知3a8=5a13,且a1>0,Sn为其前n项和.则Sn中最大的是( ) {an},{bn}是两个等差数列,其前n项和分别为Sn和Tn,且Sn/Tn=(7n+2)/(n+3),则a8/b8= 等差数列an的前n项和是Sn,且a4+a8=0,则A.S4 已知等比数列{an}各项为实数且公比为q,前前n项和为Sn,S3,S9,S6成等差数列,求证：a2,a8,a5成等差数列 已知等比数列{An}的公比为q,前n项和为Sn,且S3,S9,S6成等差数列求证A2,A8,A5成等比数列 等差数列{an}前n项和为sn,若a5+a8=20,则s12=? 已知等差数列an前n项和为sn,a1=-4,a8=-18