一轮资料资源简介：

3.在各项都为正数的等比数列{an}中,若a5•a6=9,则log3a1+log3a2+log3a3+…+log3a10等于(    )
A.8                     B.10                  C.12                D.2+log35
答案：B
解析：log3a1+log3a2+…+log3a10=log3(a1a2…a10)=log3(a5a6)5=log395=10.
4.已知{an}是等比数列,且an>0,a2a4+2a3a5+a4a6=25,那么a3+a5的值等于(    )
A.5                     B.10                  C.15                D.20
答案：A