1.设等差数列{an}的公差为d(d≠0),若n>1(n∈N*),比较a1a(n+1)与a2an的大小
1.设等差数列{an}的公差为d(d≠0),若n>1(n∈N*),比较a1a(n+1)与a2an的大小
设等差数列a1,a2,a3,..an,...的公差为d,则第n项an与第1项a1的关系为an+a1+(n-1)d.
设公差为d的等差数列{an}的前n项和为Sn,若a1=1,-2/17
设数列{an}是公差为d的等差数列,a3+a5=2,S20=150,又bn=2an−2an+1(n∈N*)
已知非负等差数列{an}的公差d不为0,前n项和为Sn,设m,n,p∈N*,且m+n=2p (1)求证:1/Sn+1/S
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}的公差d>0,设{an}的前几项和为Sn,a1=1,S2×S3=36,求m,k(m,k∈N*)
等差数列中,公差d≠0,|a11|=|a51|,a20=22,设{an}前n项和为Sn,{|an|}前n项和为Tn.(1
向量与数列问题,急救已知数列{An}是公差为d(d≠0)的等差数列.其前n项和为Sn(1)若A1=1,向量OPn=(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.
已知等差数列{an}的公差d>0,设{an}的前n项和为Sn,a1=1,S2•S3=36.
已知{(an}是等差数列,d为公差且不为0,a1和d均为实数,它的前n项和记作Sn,设集合A={〔an,Sn/n〕︱n∈