题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021855-44692.png)
(1)求数列{an}的通项公式;
(2)记数列{an}的前n项和为Sn,且Tn=
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021856-72644.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021856-86030.png)
解析
∴x=1,或x=2.∴Dn内的整点在直线x=1和x=2上.
记直线y=-nx+3n为l,l与直线x=1、x=2的交点的纵坐标分别为y1,y2.
则y1=-n+3n=2n,y2=-2n+3n=n.∴an=3n(n∈N*).
(2)∵Sn=3(1+2+3+…+n)=
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021856-58162.png)
∴Tn=
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021856-66847.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021856-33578.png)
∴当n≥3时,Tn>Tn+1,且T1=1<T2=T3=
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021856-86030.png)
于是T2,T3是数列{Tn}中的最大项,故m≥
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021856-86030.png)
核心考点
试题【设不等式组所表示的平面区域为Dn,记Dn内的整点个数为an(n∈N*)(整点即横坐标和纵坐标均为整数的点).(1)求数列{an}的通项公式;(2)记数列{an}】;主要考察你对等差数列等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021602-86565.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021603-93775.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021603-78746.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021603-44209.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021604-14170.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021604-68728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021604-31842.png)
(1)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021604-82661.png)
(2)设
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021605-92982.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021605-44318.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021549-21936.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021549-83265.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021550-98905.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021550-63476.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021550-71944.png)
(1)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021549-21936.png)
(2)设
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021550-59653.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021551-20372.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021551-38442.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021551-77096.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021551-38119.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021527-16376.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021527-97785.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021527-11977.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021528-47381.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021528-56261.png)
(1)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021527-16376.png)
(2)设
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021528-19195.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021528-48543.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021527-11977.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021528-67468.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021503-61764.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021503-13099.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021504-17112.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021504-94636.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021504-36230.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021504-85239.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021504-30274.png)
(1)求证:数列
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021503-13099.png)
(2)设数列
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021503-13099.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021505-18135.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021505-92064.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021505-96921.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021505-22485.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021504-94636.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021506-99322.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021506-24931.png)
(3)在满足(2)的条件下,求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021506-92276.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021504-17112.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021507-45117.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021435-57445.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021435-80392.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021435-75346.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021435-64351.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009021436-56111.png)
最新试题
- 1下列各组词语中,没有错别字的一组是( )A.誓愿白练仿绸负曲衔冤B.篡夺诡计珠玑良晨美景C.玉簪寻觅摞髻暗香盈袖 D
- 2(17分)可视为质点的小球A、B静止在光滑水平轨道上,A的左边固定有轻质弹簧,B与弹簧左端接触但不拴接,A的右边有一垂直
- 3下列说法正确的是A.经济因素对人口迁移的影响是通过人们对自然条件的改造而实现的B.经济发展水平较高的地区,人口迁入率往往
- 4观察漫画中同学的表现,你认为这位同学应该( ) ①集体利益为重,自觉服从集体的需要 ; ②抓紧一切
- 5Exhibition: Little Angels Date: January 10 -- September 13,
- 6蒸馒头时,为使馒头暄软多孔,要向面团中加入一些: A.乳酸细菌B.酵母菌C.青霉D.曲霉
- 7从南极上空向下看,甲飞机沿南纬600逆时针方向飞行,从北极上空向下看,乙飞机沿北纬600逆时针方向飞行,下列叙述正确的是
- 8为了调查某工厂工人生产某种产品的数量情况,随机抽查了100名工人一天内生产该产品的数量,产品数量的分组区间为,由此得到频
- 9以下数字指时间(即时间间隔)的是( )A.刘翔百米跨栏记录为12.88sB.某中学的作息表上写着,预备2:00C.中央
- 10 I could not remember the text . [ ]A. However har
热门考点
- 1下面漫画《失衡》要求发挥财政的作用有[ ]A.促进社会公平B.改善人民生活C.健全社会保障体系D.促进经济平稳运
- 2秦朝郡县制是有利于巩固国家统一和中央集权的制度,主要是由于( )A.郡县官吏必须由上一级任命并对上一级负责B.郡
- 3补写下列文学常识或名篇名句中的空缺部分。(8分)小题1:《马说》的作者 是唐代文学家、诗人,“唐宋八大家
- 4海岸线曲折,多峡湾与岛屿,海湾常深入内陆且两岸陡峻,这是某种地质作用形成的海岸景观;北部地区有极昼和极夜现象。形成该种海
- 5金属板A、B水平放置,且分别带等量异号电荷.一粒子从B板左侧斜向上射入两板间,轨迹如图所示,忽略两板边缘电场和重力对粒子
- 6书面表达。 你刚进入高中新的学习生活,某英文报欲征集有关高一新生学习经验的小短文。请以“How to Be a
- 7-I not Lily . My name Lucy.A.am, amB.is, isC.am
- 8观察下列图片(12分)请回答:(1)上面三幅图片反映的历史现象是什么?对此你有什么更深层次的思考?(6分)(2)列宁曾经
- 9– Can you go to the movies with me?– , but I haven’t f
- 10下列关于Na2CO3的分类叙述错误的是( )A.Na2CO3俗名为纯碱,故它属于碱类B.Na2CO3属于含氧酸盐C.Na