已知数列
的前
项和为
,且
,
,则若存在正整数
使得
成立,则实数
的取值范围是__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b28ef6f1b2279af482557a8ea46f2e43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a425978da20cebf8c4c63953579e7b35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7462c80ba563bc747cdf136b1156109d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc3ede255fecf6aba650c90309d62670.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a425978da20cebf8c4c63953579e7b35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db733494e8d0b6f02d9d53343306fdf5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08075b3b73dd2609baad69a496fdd9a8.png)
更新时间:2018-04-27 11:02:21
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填空题-单空题
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较难
(0.4)
名校
【推荐1】正整数数列
满足
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,
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________ .
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【推荐2】记数列
的前
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,都有
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解题方法
【推荐1】已知数列
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①当
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____________ ;
②若对任意的
,
恒成立,则
的最大值为_____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.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/075bd5b0a8ef9de112ff558d33898df7.png)
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbfc875ca919921e8f63a6fca648561b.png)
②若对任意的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f093c61867ee4ce75f951d46b9b123.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe117de8aed8605d27303f81f06c8eed.png)
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【推荐2】已知数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c91bb1a62b7bf8baf2ce0dbbf525f77d.png)
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