等差数列{an}中,Sn是{an}前n项和,已知S6=2,S9=5,则S15=( )
已知Sn是等比数列{An}的前N项和,S3,S9,S6成等差数列,则
设Sn是等比数列{an}的前n项和,S3,S9,S6成等差数列,且a2+a5=2am,则m等于( )
已知等比数列{an}的公比为q,前n项和为Sn,且 S3,S9,S6 成等差数列,则q^3=( )
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=______.
填空题等差数列{an}的前n项和为Sn,若S3=3,S6=9,则S9=( ).
设Sn是等比数列{an}的前n项和,S3,S9,S6成等差数列.
1.设等比数列{an}的前n项和为Sn,若S6/S3=3,则S9/S6=?
设等比数列an的前n项的和为Sn,若S6/S3=3,则S9/S6=
已知等比数列{an}的公比为q,前n项的和为Sn,且S3,S9,S6成等差数列.则q3的值是( )
在等差数列{an}中,已知sn是其前n项和,且a1一a4一a8一a12十a15=2,则s15=
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Sn是等差数列{an}的前n项和,已知S6=36,Sn=324,Sn-6=144,则n=( )