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各项均为正数的等比数列{{an}的前n项和为Sn,若a3=2,S4=5S2,则a...
各项均为正数的等比数列{{an}的前n项和为Sn,若a3=2,S4=5S2,则a1的值为 ,S4的值为 .
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D.
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