(15分)已知數(shù)列
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、
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滿足:
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,
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,
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。
(1)求數(shù)列
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的通項公式;
(2)若
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,求數(shù)列{
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}的前n項和
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。
解(1)∵
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;
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,
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,∴
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∴
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,∴
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∴
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,∴
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∴
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(2)∵
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,∴
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=
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∴
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+……
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=
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