因为等比数列中,
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,故可知答案为6.
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科目:高中数学
来源:不详
题型:解答题
(本小题满分14分)
已知数列
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中,

(1)求证:数列

是等比数列;
(2)设
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,求证:数列

的前

项和
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.
(3)比较
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与
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的大小(
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)。
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科目:高中数学
来源:不详
题型:解答题
(本题满分12分)在等比数列

中,

,

(1)求出公比

(2)求出
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科目:高中数学
来源:不详
题型:解答题
(本小题满分14分)
在等比数列

(1)求数列{a
n}的通项公式;
(2)求数列{a
n}的前5项的和

;
(3)若

,求T
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科目:高中数学
来源:不详
题型:解答题
已知数列

中,
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,其前

项和

满足:

,令

.
(1) 求数列

的通项公式;
(2) 若

,求证:

;
(3) 令

,问是否存在正实数

同时满足下列两个条件?
①对任意
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,都有
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;
②对任意的

,均存在

,使得当

时总有
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.
若存在,求出所有的
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; 若不存在,请说明理由.
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科目:高中数学
来源:不详
题型:单选题
设等比数列

各项均为正数,且

,则

A.12 | B.10 | C.8 | D. |
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