名校
解题方法
1 . 北京天坛圜丘坛的地面由石板铺成,最中间的是圆形的天心石,围绕天心石的是9圈扇环形的石板,从内到外各圈的石板数依次为
,
,
,…,
,设数列
为等差数列,它的前n项和为
,且
,
,则
( )
![](https://img.xkw.com/dksih/QBM/2022/4/15/2958580988510208/2961371128455168/STEM/1fff355ed6674936b772cb53af0632d6.png?resizew=257)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e88093a749c0d46e0ee931ecfaff925.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c1ccc6c74b8754e9bcbb3f39a11b6f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc858b7a95c5006a44067022da09f667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/039e449a6d9e76e0497bf2672740f801.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68b9eba619fd20aa0f1b94f439e8c6fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc4e70b360f988fdbd92300ab22c4613.png)
![](https://img.xkw.com/dksih/QBM/2022/4/15/2958580988510208/2961371128455168/STEM/1fff355ed6674936b772cb53af0632d6.png?resizew=257)
A.189 | B.252 |
C.324 | D.405 |
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