数列{an}前N项和Sn.3Sn =(an-1),(n)为下标.求证{an}为等比数列
数列{an}前N项和Sn.3Sn =(an-1),(n)为下标.求证{an}为等比数列
已知数列{An},Sn是其前n项和,且满足3An=2Sn+n,n为正整数,求证数列{An+1/2}为等比数列
设数列An的前n项和为Sn,已知a1=1,An+1=Sn+3n+1求证数列{An+3}是等比数列
等比数列an的前n项和为sn,sn=1+3an,求:an
数列{an}前n项和为Sn,且an+Sn=-2n-1 证明{an+2}是等比数列
数列{an}前n项和为Sn,且Sn=n-5an-85,证明{an-1}是等比数列
已知数列an的前n项和公式为Sn=kq^n-k,求证数列an为等比数列
数列an的前n项为sn,已知2an-2^n=sn.求证an-n·2^(n-1)是等比数列
数列An的前n项和为Sn,已知A1=1,An+1=Sn*(n+2)/n,证明数列Sn/n是等比数列
设数列an的前n项和为Sn,a1=1,an=(Sn/n)+2(n-1)(n∈N*) 求证:数列an为等差数列,
已知数列an的前n项和为sn,且sn+an=n^2+3n+5/2,证明数列{an-n}是等比数列
数列{an}前n项和为Sn,且2Sn+1=3an,求an及Sn