(本小題滿分12分,(
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333363172.png)
1)小問6分,(2)小分6分.)
已知函數(shù)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333378753.png)
,數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333425460.png)
滿足
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333441476.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333456623.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333472519.png)
.
(1)求證:
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333503718.png)
;
(2)求證:
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232043335191846.png)
.
(1)首先用數(shù)學(xué)歸納法證明
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333534617.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333550341.png)
時(shí),顯然成立;
假設(shè)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333581959.png)
,則
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333597629.png)
,因?yàn)?img src="http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333628746.png" style="vertical-align:middle;" />在
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333644428.png)
上單調(diào)遞增,所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232043336901070.png)
即也有
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333706664.png)
成立.
從而
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232043337371261.png)
,所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204333753484.png)
...............6
(2)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232043337683055.png)
所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232043338002031.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232043338153473.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232043338622673.png)
...............12
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,
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![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204117736357.png)
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的等差中項(xiàng),
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![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823203740412587.png)
有
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有
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來源:不詳
題型:解答題
..(本題滿分18分)本題共有3個(gè)小題,第1小題滿分4分,第2小題滿分6分,第3小題滿分8分。
設(shè)函數(shù)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757283946.png)
,數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757299484.png)
滿足
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757314991.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757345833.png)
。
⑴求數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757299484.png)
的通項(xiàng)公式;
⑵設(shè)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232027574081308.png)
,若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757423596.png)
對(duì)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757439523.png)
恒成立,求實(shí)數(shù)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757455267.png)
的取值范圍;
⑶是否存在以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757470315.png)
為首項(xiàng),公比為
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757486915.png)
的等比數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757517582.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757533518.png)
,使得數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757517582.png)
中每一項(xiàng)都是數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757299484.png)
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![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823202757579498.png)
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來源:不詳
題型:解答題
(1)等比數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200405669480.png)
中,對(duì)任意
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200405762437.png)
,
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時(shí)都有
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200405903514.png)
成等差,求公比
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200405981311.png)
的值
(2)設(shè)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406090388.png)
是等比數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200405669480.png)
的前
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406121277.png)
項(xiàng)和,當(dāng)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406199545.png)
成等差時(shí),是否有
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406215525.png)
一定也成等差數(shù)列?說明理由
(3)設(shè)等比數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200405669480.png)
的公比為
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200405981311.png)
,前
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406121277.png)
項(xiàng)和為
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406090388.png)
,是否存在正整數(shù)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406511313.png)
,使
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406527600.png)
成等差且
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406542538.png)
也成等差,若存在,求出
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200406511313.png)
與
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823200405981311.png)
滿足的關(guān)系;若不存在,請(qǐng)說明理由
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