设
为等差数列
的前
项和,
.则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81d2fa0b8ee732f41262ec0bb194e10b.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ee71c24bbd563a940edae7eb896718e.png)
![](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/ce806bae0bb0d802f7737f57833a49d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81d2fa0b8ee732f41262ec0bb194e10b.png)
2008高三·甘肃·竞赛 查看更多[1]
(已下线)2008年全国高中数学联赛甘肃赛区预赛试题
更新时间:2018-12-25 14:50:33
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【知识点】 数列求和