1 . 已知
是等差数列,若它的首项
,
,
,则使这个数列的前
项和
最大的自然数
是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/390636a89883bd64bf8da9bf8654aff9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a65de2781c62bb9a9cf8e7e43f3d87fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1344061104c69d9deb0dd089ebcc26a9.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.2006 | B.2007 | C.2008 | D.2009 |
您最近一年使用:0次
2 . 设等差数列
的公差为
,若
,比较
与
的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90bfe21c96489cb30c544d49ddb4c1c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c5296a79e570a8e36405ef5048bd5d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f539f12520ecf5d9275a12cfd58b949.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64b31d6089b86cab5ee83d6aa2c7d96c.png)
您最近一年使用:0次