设等差数列{an}的前n项和为Sn,且a1=2,a3=6,若Sk=110,求k的值.
设Sn为等差数列{an}的前n项和,若a1=1,a3=5,Sk+2-Sk=36,则K的值为
设Sn为等差数列{an}的前n项和,若a1=1,公差d=2,Sk+1-Sk=24,求K=多少?
设Sn为等差数列{an}的前n项和,若a1=1,公差d=2,Sk+2-Sk=24,则k=?
设Sn为等差数列{an}的前n项和,若a1=1,公差d=2,Sk+2-Sk=24,则k=( )
设等差数列an的前n项和为Sn,且a1=2,a3=6
设Sn为等差数列{an}的前n项和,若a1=2,公差d=2,Sk+2-Sk=26
等差数列{an}的前n项和为Sn,设S3=12,且2a1,a2,a3 1成等比数列,求Sn?
等差数列an的前n项和为Sn,设S3=122,且2a1.a2.,a3+1成等比数列,求Sn
记等差数列{an}的前n项和为Sn,设S3=12,且2a1,a2,a3+1成等比数列,求Sn.
设等差数列An的前n项和为Sn,若Sm=Sk=b则Sm+k=
设数列{an}的前n项和为Sn,满足2Sn=an+1-2^n+1+1,且a1,a2+5.a3成等差数列
等差数列啊!设{an}是公差不为0的等差数列,a1=2,且a1,a3,a6成等比数列,则其前n项和Sn=?