![](https://static.youtibao.com/asksite/comm/h5/images/m_q_title.png)
[单选题]
下列各数列中,是等比数列的是()
A.-1,1,-1,1
B.2,4,6,8
C.1, 1/2,1/4,1/6
D.3,5,7,9
![](https://static.youtibao.com/asksite/comm/h5/images/m_q_a.png)
A、-1,1,-1,1
![](https://static.youtibao.com/asksite/comm/h5/images/solist_ts.png)
A.-1,1,-1,1
B.2,4,6,8
C.1, 1/2,1/4,1/6
D.3,5,7,9
A、-1,1,-1,1
A.2 , 4 , 6 , 8 ,…
B.-3 , 3 , -3 , 3 ,…
C.1 , 0 , 1 , 0 ,…
D.-2 , -4 , 8 , 16 , -32 , -64
已知等比数列{an}中,a1=16,公比q=(1/2)
(Ⅰ)求数列{an}的通项公式;
(Ⅱ)若数列{an}的前n项的和Sn=124,求n的值
已知数列{an}是等比数列,且a>0,a2a4+2a3a5+a4a6=25,那么a3+a5的值等于
A.5
B.10
C.15
D.20
数列{an}的通项公式为an=3n,则{an}()
A.是等差数列
B.是首项为1的等比数列
C.是首项为3的等比数列
D.不是等比数列