在等比数列{a n }中,a n >0,(n∈N + )且a 3 a 6 a 9 =8,则log 2 a 2 +log 2 a 4 +log 2 a 6 +log 2

2025-05-14 13:09:26
推荐回答(1个)
回答1:

设等比数列的首项为a,公比为q,则a 3 a 6 a 9 =aq 2 ?aq 5 ?aq 8 =a 3 ?q 15 =(aq 5 3 =2 3 =8,得aq 5 =2;
而log 2 a 2 +log 2 a 4 +log 2 a 6 +log 2 a 8 +log 2 a 10 =
log a 2 ? a 4 ? a 6 ? a 8 ? a 10    2
=
log (a q 5 ) 5 2
=
log 2 5 2
=5
故答案为5