試題分析:由于
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,
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,且
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,所以
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,故選C.
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項和;2.等差數(shù)列的性質(zhì)
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科目:高中數(shù)學
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題型:解答題
已知數(shù)列
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為遞增等差數(shù)列,且
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是方程

的兩根.數(shù)列

為等比數(shù)列,且

.
(Ⅰ)求數(shù)列
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的通項公式;
(Ⅱ)若
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,求數(shù)列
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的前
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項和
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.
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已知數(shù)列

各項為非負實數(shù),前n項和為
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,且

(1)求數(shù)列

的通項公式;
(2)當

時,求
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.
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已知等差數(shù)列

的首項
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,公差
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.且
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分別是等比數(shù)列

的
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.
(Ⅰ)求數(shù)列
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與
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的通項公式;
(Ⅱ)設數(shù)列

對任意自然數(shù)

均有
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…
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成立,求
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…
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的值.
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數(shù)列

的首項為
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,
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為等差數(shù)列且

.若則
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,
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,則
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( )
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已知數(shù)列

的前
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項和為
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,且
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,則
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取最小值時,
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的值是( )
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科目:高中數(shù)學
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等比數(shù)列

的前
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項和為

,已知對任意的
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,點

均在函數(shù)
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且

均為常數(shù))的圖像上.
(Ⅰ)求
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的值;
(Ⅱ)當
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時,記

,求數(shù)列

的前
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項和
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.
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已知數(shù)列

等于( )
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科目:高中數(shù)學
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已知等比數(shù)列

中,各項都是正數(shù),且
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成等差數(shù)列,則
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等于 ( )
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