11-12高一下·四川攀枝花·阶段练习
解题方法
1 . 等差数列
中,
,
,且
,
是前
项和,则下列判断正确的有_______ .
①数列
的最小项是
;
②
,
,
;
③
先单调递减后单调递增;
④当
时,
最小;
⑤
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88b8be47f727e800bef9b647254dd432.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b499db552a74e4d609391271dcf72ad2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de0db09c9753bb386bdf8fd9c7ae6dec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
①数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/486cddc710aec81c76b5b395446eaa00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ad3bdc2cf20eefdf5b999239cc6f935.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce868ac245a30cc99db2b35b2fabc545.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
④当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c345907ebe27888332b1b44c666cc47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
⑤
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ebaeb63ef37c1d92f44777ac97b58.png)
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