等比数列{an}的各项为正数,且3是a5和a6的等比中项,则a1a2…a10=( ) A.39 B.310 C.311 D.312
问题描述:
等比数列{an}的各项为正数,且3是a5和a6的等比中项,则a1a2…a10=( )
A. 39
B. 310
C. 311
D. 312
答
∵等比数列{an}的各项为正数,且3是a5和a6的等比中项,
∴a5•a6=9,
则a1a2…a10=(a5 •a6)5=95=310,
故选:B.