1.已知各项均为正数的等比数列{an}的前n项和为Sn,且S3=14,a3=8,则a6等于
( )
A.16 B.32 C.64 D.128
2.(2020·赣州模拟)Sn是等比数列{an}的前n项和,若S4,S3,S5成等差数列,则
{an}的公比q的值为 ( )
A. B.-2 C.1 D.-2 或1
3.已知等比数列{an}满足a1=3,a1+a3+a5=21,则a3+a5+a7= ( )
A.21 B.42 C.63 D.84
4.(2019·全国卷Ⅲ)已知各项均为正数的等比数列{an}的前4项的和为15,且a5=3a3+4a1,则a3= ( )
A.16 B.8 C.4 D.2
5.已知Sn是等比数列{an}的前n项和,若存在m∈N*,满足=9,=,则数列{an}的公比为
