等差数列
中,已知
且公差
,则其前
项的和
取得最小值时
的值为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c588eaa0bd3a975a4012ee3ba4bc0e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4ce64685821c3e55c07f151996ca8c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
A.7 | B.8 | C.9 | D.10 |
更新时间:2017-11-10 21:31:22
|
【知识点】 求等差数列前n项和的最值
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单选题
|
较易
(0.85)
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解题方法
【推荐1】已知等差数列
中,
,且公差
,则其前
项和取得最大值时
的值为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b22f0c32baa2859f824db6d18ae0f91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2d8bbb4a09e0ac86bbae46222a90841.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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单选题
|
较易
(0.85)
【推荐2】等差数列{an}的前n项和为Sn,若a1=23,S6=12a8,则使Sn达到最大值的n是( )
A.10 | B.11 | C.12 | D.13 |
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