若三个数a+log29，a+log23，a+log281成等比数列则其公比的值是

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问题填空题

若三个数^a+log₂9，a+log₂3，a+log₂81成等比数列则其公比的值是______．

答案

由等比数列性质，得（a+log₂3）²=（a+log₂9）（a+log₂81），

令log₂3=t则（a+t）²=（a+2t）（a+4t），解得a=-

t，

∴公比q=

a+t

a+2t

=-3

故答案为：3

判断题

一般小型企业适合进入投资和收益都较低的群体，实力雄厚的企业则可以考虑进入竞争性较强的群体。( )

单项选择题

In a traffic separation scheme, when joining a traffic lane from the side, a vessel shall do so（）.

A.only in case of an emergency or the engage in fishing within the zone

B.as nearly as practical at right angles to the general direction of traffic flow

C.at as small an angle as possible

D.only to anchor within the zone