题目
题型:不详难度:来源:
(8,12,10,7),(16,24,20,14,9),…。并顺次称其为第1群,第2群,第3群,第4群,…。
⑴第7群中的第2项是: ;
⑵第n群中n个数的和是: 。
1 | 3 | 5 | 7 | 9 | … |
2 | 6 | 10 | 14 | 18 | … |
4 | 12 | 20 | 28 | 36 | … |
8 | 24 | 40 | 56 | 72 | … |
16 | 48 | 80 | 112 | 114 | … |
… | … | … | … | … | … |
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025754-81756.gif)
解析
核心考点
试题【如图所示,将数以斜线作如下分群:(1),(2,3),(4,6,5),(8,12,10,7),(16,24,20,14,9),…。并顺次称其为第1群,第2群,第3】;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/20191013/20191013025737-79820.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025737-25392.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025737-66200.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025738-72740.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025738-61436.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025738-17178.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025738-84342.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025739-93836.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025739-76566.gif)
其中
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025739-80383.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025739-55746.gif)
(1)若数列
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025737-66200.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025739-55746.gif)
(2)令
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025739-55086.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025740-43982.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025740-59249.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025740-45260.gif)
(3)试研究数列
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025737-66200.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025733-35645.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025733-10394.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025733-70990.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025733-30750.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025734-61287.gif)
A.充分不必要条件 | B.必要不充分条件 |
C.充要条件 | D.既不充分也不必要条件 |
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025729-45929.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025729-25266.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025729-99877.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025729-54965.gif)
根据上面的几个等式,试归纳出更一般的结论: ▲ .
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025721-88027.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025721-21276.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025721-98666.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025722-78854.gif)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025711-71956.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025712-28849.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025712-98760.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025712-64861.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025711-71956.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025712-69434.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025712-21881.gif)
(2)记
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025712-79528.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025712-92913.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013025711-71956.gif)
最新试题
- 1默写杜甫《望岳》的颈联和尾联。(4分)_________________________________________
- 2依据材料,完成下列各题。下图为印度著名的乔塔那格浦尔工业区和中国的沪宁杭工业区。(1)乔塔那格浦尔工业区作为一个形成较晚
- 3某种生物的体细胞中有16条染色体,它的一个体细胞连续分裂两次,得到4个子细胞,每个子细胞中的染色体数目是( )A.4条
- 4一些细菌能形成休眠体来抵抗不良环境,休眠体的名称是[ ]A.鞭毛B.荚膜C.芽孢D.孢子
- 5零上13℃记作+13℃,零下2℃记作[ ]A.2B.-2C.2°CD.-2°C
- 6给出下列命题:①若“且”为假命题,则、均为假命题;②、,;③“,”的否命题是“,”;④在中,“”是“”的充要条件.其中正
- 7—What do you think of the gift ?—I like it a lot, but it’s t
- 8函数的图象一定经过点( )A.(3,5); B.(-2,3);C.(2,7); D.(4,10).
- 9从词类活用的角度看,下列句中加粗的字与其他三项不同的是[ ]A.不知将军宽之至此也
- 10已知|a|=3,|b|=4,ab>0,则a﹣b=( ).
热门考点
- 1一闭合线圈在匀强磁场中做匀角速转动,角速度为240π rad/min,当线圈平面转动至与磁场平行时,线圈的电动势为2.0
- 2如图,不等长的两条对角线AC、BD相交于点O,且将四边形ABCD分成甲、乙、丙、丁四个三角形.若AOOC=BOOD=12
- 3The rain started an hour ago. It"s still raining now. It
- 4(本小题共12分)圆O: 内有一点P(-1,2),AB为过点p且倾斜角为的弦,(1) (6′)当=135时,求AB的长;
- 5The officer ______ those who lost sons or husbands in the mi
- 6某市面积为l000平方千米,人口为25万人该市人口密度为[ ]A.25人/平方千米B.2.5人/平方千米C.25
- 7如图,△ABC的角平分线AD、中线BE相交于点O.则:①AO是△ABE的角平分线;②BO是△ABD的中线;③DE是△AD
- 8At first I was a little worried, but I"m glad that things ha
- 9与“入乡随俗”哲学寓意相对立的是 ( )①随机应变 ②郑人买履 ③随心所欲 ④刮目
- 10同时掷3枚硬币,那么互为对立的事件是( )A.至少有1枚正面和最多有1枚正面B.最多有1枚正面和恰有2枚正面C.不多于