1 . 将给定的一个数列
:
,
,
,…,按照一定的规则依顺序用括号将它分组,则可以得到以组为单位的序列.如在上述数列中,我们将
作为第一组,将
,
作为第二组,将
,
,
作为第三组,…,依次类推,第
组有
个元素(
),即可得到以组为单位的序列:
,
,
,…,我们通常称此数列为分群数列.其中第1个括号称为第1群,第2个括号称为第2群,第3个数列称为第3群,…,第
个括号称为第
群,从而数列
称为这个分群数列的原数列.如果某一个元素在分群数列的第
个群中,且从第
个括号的左端起是第
个,则称这个元素为第
群中的第
个元素.已知数列1,1,3,1,3,9,1,3,9,27,…,将数列分群,其中,第1群为
,第2群为
,第3群为
,…,以此类推.设该数列前
项和
,若使得
成立的最小
位于第
个群,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c57bbef89a37f1a3808c0ceeac0c22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](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/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/daf464629fa321a6ff7401ab79f07083.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f65fc200f10b97588a0c9896277c9c64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5da4cd81500bdb43118150dbdb1541e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a37a59558292ad6b3d0978bfd7484990.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed27bd9fefa33530b41362726d899cf1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/472c5ca669e0c8f51b7811a8a32d4ecb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/833a13fbc5f9f08057a2df690d8f1421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9bf6c84731e5e1bd335ecfc2d36c3d81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2e88ebfb5c0d6cce558b515be06404d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe9ba4ded780c5d3093a28c1f7e18e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/641540f39380bd7622d83ede884a2169.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba0a8af6935cf6d8708c9a468eac6483.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c57bbef89a37f1a3808c0ceeac0c22.png)
A.11 | B.10 | C.9 | D.8 |
您最近一年使用:0次
2020·全国·模拟预测
2 . 秦九韶在《数书九章》中提及了山高的测量方法:如图,已知树高
米,距山
米,人(人站在坡面上)在距树
米处望山,人目
、树顶
、山顶
在一条直线上,根据图可得
,得
,即可求出山高.此方法为我们提供了一种人在山坡上任选一点测量山高的方法,若
,
,
,
,则目高
( )(山高为
,目高
为眼睛到山脚的重直距离)
![](https://img.xkw.com/dksih/QBM/2021/1/12/2634695124287488/2635389340622848/STEM/5a76a197-9116-4ce3-859f-b8262c9a36a9.png?resizew=313)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b715e7842b95f654f16056a7c7f2abe9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/193e7005c259d6e89e5bcce71ffea772.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/14c9ae7784e1e62d8135c84bd3d2e368.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65397f11ea8af736f38debadf420c4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86718fa3bd81961f00798692fbf86db1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68ced0786c01314bbb90a24cb900492f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f642cfbe71ace1a1c439dafa2b82dc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea5e7d9414ee7412c4888ff30384e48d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53b95463a97c60db3250cb641bf6523d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://img.xkw.com/dksih/QBM/2021/1/12/2634695124287488/2635389340622848/STEM/5a76a197-9116-4ce3-859f-b8262c9a36a9.png?resizew=313)
A.4.91米 | B.3.91米 | C.2.91米 | D.1.91米 |
您最近一年使用:0次