设{an}是公比为q的等比数列,Sn是它的前n项和.若{Sn}是等差数列,则q=______.
设{an}是公比为q的等比数列,Sn是它的前n项和.若{Sn}是等差数列,则q=______.
若Sn是公比为q的等比数列{an}的前n项和,且S4,S6,S5成等差数列,则公比q=______.
设Sn是等比数列{an}的前n项和,S3,S9,S6成等差数列,则公比q=______.
设等比数列{an}的公比为q,前n项和为Sn,若Sn+1,Sn,Sn+2成等差数列,则q=?
设等比数列{an}的公比为q,前n项和为Sn,若Sn+1,Sn,Sn+2成等差数列,则公比q为( )
设等比数列{An}的公比为q,前n项和为Sn,若Sn+1,Sn,Sn+2成等差数列,则q的值为() 我知道答案是-2,可
设数列an为公比为q的等比数列,它的前n项和为sn,若数列sn为等差数列,则q的值
已知Sn是等比数列{an}的前n项和,设公比为q,且S3,S9,S6成等差数列.
设等比数列 {an} 的公比为q,前n项和为Sn,若S(n+1),Sn,S(n+2)成等差数列,则q=
设等比数列{an}的公比为q,前n项和为Sn,若Sn+1,Sn,Sn+2成等差数列,则q等于多少?若an=1,求sn前n
设(an)是等差数列,a1=1,Sn是前n项和,(bn)为等比数列其公比q的绝对值小于1
设Sn是等比数列的前n项和,若S3,S9,S6成等差数列,这an的公比q为多少