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科目:高中数学
来源:不详
题型:解答题
数列
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的前n项和为S
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,点(a
n,S
n)在直线y=2x-3n上.
(1)若数列
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;
(2)求数列
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的通项公式;
(3)数列

适合条件的项;若不存在,请说明理由.
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科目:高中数学
来源:不详
题型:单选题
设
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=
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
,n

N*,

>0,令

则数列

为( )
A.公差为正数的等差数列 | B.公差为负数的等差数列 |
C.公比为正数的等比数列 | D.公比为负数的等比数列 |
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科目:高中数学
来源:不详
题型:单选题
在等差数列

中,

,

,记数列
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的前

项和为

,若

对
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恒成立,则正整数

的最小值为
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科目:高中数学
来源:不详
题型:单选题
在等差数列{a
n}中,已知a
4+a
8=16,则该数列前11项和S
11=
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科目:高中数学
来源:不详
题型:填空题
已知

是数列{

}的前

项和,且满足

则数列{

}通项公式
.
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科目:高中数学
来源:不详
题型:单选题
已知等差数列{a
n}的前n项和为S
n,a
5=5,S
5=15,则数列

的前100项和为
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科目:高中数学
来源:不详
题型:填空题
设等差数列

的前
n项之和为

,已知

,则

_______.
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