已知等比数列
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的前三项为1,
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,2,则
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( )
A.4 | B. | C. | D.8 |
比例中项为
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,代用等比数列的公式即可得8
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科目:高中数学
来源:不详
题型:解答题
(本小题满分12分)设
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等比数列
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的前
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项和,且
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(Ⅰ)求
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数列
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的通项;
(Ⅱ)设
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,求数列
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的前
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.
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中,
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是等比数列;
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的通项公式
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
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
的前
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的前
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项和
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科目:高中数学
来源:不详
题型:单选题
在等比数列
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中,
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,前
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项和为
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,若数列
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也是等比数列,
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