(Ⅰ)
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(Ⅱ) 證明略
解:(Ⅰ)由

得
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兩式相減得

即

∴

即

…………(3分)
故數(shù)列{

}是從第2項(xiàng)起,以

為首項(xiàng),2為公比的等比數(shù)列
又

∴

故

又

不滿(mǎn)足

∴

………(6分)
(Ⅱ) 證明:由

得

則


, …………(7分)
∴

+

�、�
從而

+

�、凇 �9分)
①-②得:

故

…(11分)
∴

………(12分)
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
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
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
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
與前

項(xiàng)和

;
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
的前

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
的前3項(xiàng),記

的前

項(xiàng)和為

, 若存在

, 使對(duì)任意

總有

恒成立, 求實(shí)數(shù)
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
是各項(xiàng)均不為
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
,
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為其前
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項(xiàng)和,且滿(mǎn)足

,

.?dāng)?shù)列

滿(mǎn)足

,

為數(shù)列

的前
n項(xiàng)和.
(1)求

、

和

;
(2)若對(duì)任意的

,不等式

恒成立,求實(shí)數(shù)

的取值范圍;
(3)是否存在正整數(shù)


,使得

成等比數(shù)列?若存在,求出所有

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已知等差數(shù)列

滿(mǎn)足

,

,

,則

的

值為
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將正偶數(shù)排列如下表,其中第

行第

個(gè)數(shù)表示

(i

N
*,j

N
*),例如

,若

,則
▲ .

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設(shè)


(1)寫(xiě)出

的遞推關(guān)系式,并求出

的通項(xiàng)公式;
(2)若

試比較

大小

并證明
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