等差数列{an}前n项和为Sn,且Sn=3n^2+n 求公差d
等差数列{an}前n项和为Sn,且Sn=3n^2+n 求公差d
等差数列{an}中,a1=3,公差d=2,Sn为前n项和,求1S
已知等差数列{an}的公差d不为零,首项a1=2且前n项和为sn
等差数列{an}前n项和为Sn=3n-2n^2,求an
等差数列an中,公差d>0,且a5+a10=0,记数列-2/an的前n项和为Sn,则使Sn
设Sn为等差数列{an}的前n项和,若a1=1,公差d=2,Sn+2-Sn=36,则n=( )
已知等差数列{an}的前n项和为Sn,Sn=kn(n+1)-n(k∈R),公差d为2.
等差数列{an}中,公差为d,已知a4=84,前n项和为Sn,且S10>0,S11
在等差数列an中,前n项和为sn,若sm=2n,sn=2m,(m,n∈N*,且m≠n),则公差d的值为多少?
若等差数列{an}的首项为a1,公差为d,前n项的和为Sn,则数列(Sn/n)为等差数列,且通项
等差数列{an}的前n项和为Sn,且S3=6,a1=4,则公差d等于
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=?