等比数列an的前n项和为sn,sn=1+3an,求:an
等比数列an的前n项和为sn,sn=1+3an,求:an
等比数列中,sn为前n项和,sn=2an—1,求an
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的前n项和为sn,an=2/3sn+2/3n,求an+1是等比数列
已知等比数列{an}的公比为q,前n项和为Sn,求[Sn*Sn+2-(Sn+1)^2]/[an*an+2]
设Sn为等比数列{an}的前n项和,已知Sn=3an+1+m,Sn-1=3an+m,则公比q=
设数列{an}的前n项和为Sn,Sn=n-an,n属于自然数.求:证明:数列{an-1}是等比数列
数列{an}前n项和为Sn,且2Sn+1=3an,求an及Sn
数列前n项和为sn,a1=1,an+sn是公差为2的等差数列,求an-2是等比数列,并求sn
已知数列{an}a1=2前n项和为Sn 且满足Sn Sn-1=3an 求数列{an}的通项公式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