问题
填空题
等比数列{an}的各项均为正数,且a4a6=9,则log3a1+log3a2+…log3a9=______.
答案
等比数列{an}的各项均为正数,且a4a6=9=a52,即a5=3,则log3a1+log3a2+…log3a9
=(log3a1+log3a9 )+(log3a2+log3a8)+(log3a3+log3a7 )+(log3a4+log3a6)+log3a5
=4(log3a4+log3a6)+log3a5=4log3(a4a6)+log3a5=4×2+1=9,
故答案为9.