等差数列an中,前n项和为Sn,且S6S8,则:
在等差数列{an}中,设前m项和为Sm,前n项和为Sn,且Sm=Sn,m不等于n,则Sm+n=?
等差数列{an}中,a1>0,前n项和为Sn,且S9>0,S10
在等差数列{an}中,Sn为其前n项和,且a1=13,S3=Sn
已知数列{an}中,a2=2,前n项和为Sn,且Sn=n(an+1)/2证明数列{an+1-an}是等差数列
已知数列{an}中,其前n项和为Sn,且n,an,Sn成等差数列(n∈N*).
等差数列An中Sn为前n项和,a4+a7=10,则S10为
若等差数列{An}的前m项和为Sm,前n项和为Sn,且Sm:Sn=m²:n²,则Am:An=?
数列{an}中,a2=2,前n项和为sn,且sn=n(an+1)/2 证明{a-an}是等差数列
已知等差数列{an}的前n项和为Sn,且a1不等于0,求(n*an)/Sn的极限、(Sn+Sn+1)/(Sn+Sn-1)
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
设等比数列{an}中,a1=256,前n项和为Sn,且Sn,Sn+2,Sn+1成等差数列,
等差数列{an}中,公差为d,已知a4=84,前n项和为Sn,且S10>0,S11