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科目:高中數(shù)學
來源:不詳
題型:單選題
已知數(shù)陣中,每行的三個數(shù)依次成等差數(shù)列,每列的三個數(shù)也依次成等差數(shù)列,若
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,則所有這九個數(shù)的和為( )
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科目:高中數(shù)學
來源:不詳
題型:解答題
(本小題滿分14分)已知數(shù)列
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是遞增數(shù)列,且滿足
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(Ⅰ)若
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是等差數(shù)列,求數(shù)列
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的通
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項公式;
(Ⅱ)對于(Ⅰ)中
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,令
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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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科目:高中數(shù)學
來源:不詳
題型:解答題
等差數(shù)列
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不是常數(shù)列,且
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,若
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構成等比數(shù)列.
(1)求
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;
(2)求數(shù)列
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前n項和
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科目:高中數(shù)學
來源:不詳
題型:單選題
已知
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為等差數(shù)列,其公差為
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,且
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是
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與
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的等比中項,
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為
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的前
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項和,
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,則
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的值為
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科目:高中數(shù)學
來源:不詳
題型:單選題
設等差數(shù)列
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的前
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項和為
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,若
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,
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,則當
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取最小值時,
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等于( )
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