1 . 差分法的定义:若数列
的前
项和为
,且
,则
时,
.例如:已知数列
的通项公式是
,前
项和为
,因为
,所以
.
(1)若数列
的通项公式是
,求
的前
项和
;
(2)若
,且数列
的前
项和分别为
,证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.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/314fa1f4da470780673cc7246974180c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0704f453b2de48d36911f7db496bbf82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9361afc7cc02253140585eedc39a695d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/677e46ecd051c92489c0d1d458932f37.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/e3bd2e55bb083a90ecba8cc98fac9536.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/237ce153a42d4e2378d5435051734cb3.png)
(1)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8bd845d1bfac72200926447db04563fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77af844c4444e536adae9bc0b1cff614.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c04f062dc12653209868713f2142fe06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee1c51f15c934050099b460b19a04f4b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/038e3af7c9f2fb642b9209415662aeff.png)
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2024-05-30更新
|
168次组卷
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2卷引用:黑龙江省伊春市铁力市第一中学校2023-2024学年高二下学期期中考试数学试卷
解题方法
2 . 如图,对于曲线
,存在圆
满足如下条件:
①圆
与曲线
有公共点
,且圆心在曲线
凹的一侧;
②圆
与曲线
在点
处有相同的切线;
③曲线
的导函数在点
处的导数(即曲线
的二阶导数)等于圆
在点
处的二阶导数(已知圆
在点
处的二阶导数等于
);
则称圆
为曲线
在
点处的曲率圆,其半径
称为曲率半径.
(1)求抛物线
在原点的曲率圆的方程;
(2)求曲线
的曲率半径的最小值;
(3)若曲线
在
和
处有相同的曲率半径,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
①圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
②圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
③曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80999542b0b1e42a23e95363667399a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92637a7e7dab461f173112dfc8fa7390.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98b40504aef42ec81163e9581efbd83b.png)
则称圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
(1)求抛物线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/344ccbf79da6ad7e3709d6fa72efb756.png)
(2)求曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f42b2a9736c8943106472a7398d2892.png)
(3)若曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2eae1b87c23b45ce5e5e74d5b1d73234.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c3c0b12482cc93dee05fbf69350cd99.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2f455ecf39764829b0bfe0a8675f1a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cbd8e10a553d5607bb8906b2cf64aaf.png)
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2024-03-22更新
|
1395次组卷
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3卷引用:广东省惠州市博罗县2023-2024学年高二下学期4月期中质量检测数学试题
3 . 已知函数
,记
的图象为曲线C.
(1)若以曲线C上的任意一点
为切点作C的切线,求切线的斜率的最小值;
(2)求证:以曲线C上的两个动点A,B为切点分别作C的切线
,
,若
恒成立,则动直线AB恒过某定点M.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/847cc4ad8e1058e49563117ef0a9f65c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51c530f4b7491b95acb8ce3eef9aa09d.png)
(1)若以曲线C上的任意一点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/caf0d139c9810361b4971904a943856b.png)
(2)求证:以曲线C上的两个动点A,B为切点分别作C的切线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1095c036b49c3327baaa2c3c7f746134.png)
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名校
4 . 平面上
个圆最多把平面分成
个区域,通过归纳推理猜测
的表达式,再利用数学归纳法证明.用数学归纳法证明的过程中,当
时,需证
( ).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63ba21f3d0cfc86d40e2e06446623ce0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/056a3376fabf84be387cf75f3bba6d2e.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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5 . 已知
与
都是定义在
上的函数,函数
图像上任意两点
,记
表示此两点连线的斜率.当
时,都有
,则称
是
的一个“T函数”.
(1)判断
是否为函数
的一个
函数,并说明理由;
(2)设
的导数为
,求证:关于
的方程
在区间
上有实数解;
(3)函数
的导函数存在记为
,即
导函数存在记为
,当
都有
,函数
是否存在T函数?若存在,请求出
的所有
函数;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942c2141d01bde6b48210c56a17fc75e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1938c093dd2fbcb752d0eb7a18d143b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d562dc22dfb3b81d0c3f88b54d063c2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e3a1467ecf286e3cadaf5aa006606f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c1dc007e36c78ab98df4cd2383b4c5d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/26d8dafc71b106f39f4e15442220897b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3861f863fc3d8703abf9e5bf97ef6117.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1938c093dd2fbcb752d0eb7a18d143b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942c2141d01bde6b48210c56a17fc75e.png)
(1)判断
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95a43b43650ed3473888a95607908644.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5ff3dc91272a2244b4d76056967e9a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/591c5b712dc14517e369be2345526fc7.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ff6838d84b68c6f0d3b93b196d9b08d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4c513ef355a637fff90a3371dc5328a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa852120429d7db38eb6266cf9d0d152.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4562f3225c98cf5cb11b47d98c9cc9c3.png)
(3)函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d98da166934830f1cfdbcd48dbfea6f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a813b5adbf5c7082561237894ba6d599.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2287352f6b9c1ef9e35d2ac6670fcbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95e82f423c1c5d304766d1a22d72f042.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/66692ec49a458f9e48c7315d03dfc37b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34367bca1e9f02459dc301e4881edbe5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942c2141d01bde6b48210c56a17fc75e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942c2141d01bde6b48210c56a17fc75e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/591c5b712dc14517e369be2345526fc7.png)
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6 . 如图,在平行六面体
中,E在线段
上,且
F,G分别为线段
,
的中点,且底面
为正方形.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/10/64aaaa44-e421-4524-b946-30f03c57691a.png?resizew=172)
(1)求证:平面
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c480d2b007fa8675efc646f91e256df2.png)
(2)若
与底面
不垂直,直线
与平面
所成角为
且
求点 A 到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcbb8f28f80f9908f58f2d152e912766.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ddd774c50250550d1c90f37ced4c0e7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/17eaf5287e999c0adfe22f544d8e0945.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/10/64aaaa44-e421-4524-b946-30f03c57691a.png?resizew=172)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7bde810ee34535aa397501889a52b44.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c480d2b007fa8675efc646f91e256df2.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0215e13a9fb5574d5194aeb9507a98aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb3f9a5da641be35117fd35ba07a6aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8946331b0a9d86e1a9c78797f3021455.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3676ef5c9bde8f56ac5880b7f4aa1d6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fda6215d1e6cb84f6a360b684634ea7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/509356b0db34d34ff0fe25337a48e16a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d5e5c12362a66c14785327a528b6f4c.png)
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2024-03-06更新
|
1603次组卷
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3卷引用:河南省南阳市西峡县第一高级中学2023-2024学年高二下学期第一次月考数学试卷
名校
解题方法
7 . (1)从等轴双曲线
上任一点
分别作两渐近线的平行线,得矩形
(如图),求证:矩形的面积为定值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99b343054b22bb3d30eeec12c3ae4d0d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2c06373f0ad9789976365ff5337cdbe.png)
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8 . 如图,在平面直角坐标系
中,半径为1的圆
沿着
轴正向无滑动地滚动,点
为圆
上一个定点,其初始位置为原点
为
绕点
转过的角度(单位:弧度,
).
表示点
的横坐标
和纵坐标
;
(2)设点
的轨迹在点
处的切线存在,且倾斜角为
,求证:
为定值;
(3)若平面内一条光滑曲线
上每个点的坐标均可表示为
,则该光滑曲线长度为
,其中函数
满足
.当点
自点
滚动到点
时,其轨迹
为一条光滑曲线,求
的长度.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/02c9643bf4dd7e04efa4644412491725.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c81b29ac8a01886b25dcef55c5f6877.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
(2)设点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2ce55c4ff508755d16c375625437027.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69218ef831edc8173b4029ea99eda87.png)
(3)若平面内一条光滑曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc031988b2a4dcd840069dbd3a1c810e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dfe48a76ae71f8925b731e8c330bdb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5d69e7fb25c60ee47440a1ece037544.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8a8bcf6ef69b6bdfc84e8472a259bf5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/016b58ad9076316abaf809dea297256a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/016b58ad9076316abaf809dea297256a.png)
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2024-03-13更新
|
1237次组卷
|
3卷引用:河南省南阳市西峡县第一高级中学2023-2024学年高二下学期第一次月考数学试卷
名校
解题方法
9 . 设点集
,从集合
中任取两个不同的点
,
,定义A,
两点间的距离
.
(1)求
中
的点对的个数;
(2)从集合
中任取两个不同的点A,
,用随机变量
表示他们之间的距离
,
①求
的分布列与期望;
②证明:当
足够大时,
.(注:当
足够大时,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3afcb129040d060714f94c0f8c48a04.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ddad3d9fdb5e9951b6a1c31f9a72a71.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5c6d29b3010fc1dc9cb640ad41d5b97.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8034add7b8011393a866a21479b62f7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80ebc8c7e32c1b561a908a36cfa2cbb5.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32efe4eff75508cb93e828c735dcb695.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1ffbdfab9dff3ff41ea474f06375032.png)
(2)从集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ddad3d9fdb5e9951b6a1c31f9a72a71.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3bcb4828b16c8e845492f1a53ddd9a9.png)
①求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
②证明:当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b59306134d26d7a35fd18bcdd401faeb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8eed2b9b1f33517499ef35e044cd104.png)
您最近一年使用:0次
2024-05-19更新
|
641次组卷
|
3卷引用:湖南省永州市部分学校2023-2024学年高二下学期6月质量检测卷数学试题
解题方法
10 . 某中学在运动会期间,随机抽取了200名学生参加绳子打结计时的趣味性比赛,并对学生性别与绳子打结速度快慢的相关性进行分析,得到数据如下表:
(1)根据以上数据,能否有99%的把握认为学生性别与绳子打结速度快慢有关?
(2)现有n
根绳子,共有2n个绳头,每个绳头只打一次结,且每个结仅含两个绳头,所有绳头打结完毕视为结束.
(i)当
,记随机变量X为绳子围成的圈的个数,求X的分布列与数学期望;
(ii)求证:这n根绳子恰好能围成一个圈的概率为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f34a85a61fcc926833ed2775f376541.png)
附:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5c1698cf3a31568a8ff6f6d4ee280e8.png)
性别 | 速度 | 合计 | |
快 | 慢 | ||
男生 | 65 | ||
女生 | 55 | ||
合计 | 110 | 200 |
(2)现有n
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e5e07bf129b073f37b553fbca100172.png)
(i)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be604061cf1591f7069472269d4c9719.png)
(ii)求证:这n根绳子恰好能围成一个圈的概率为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f34a85a61fcc926833ed2775f376541.png)
附:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5c1698cf3a31568a8ff6f6d4ee280e8.png)
0.100 | 0.050 | 0.025 | 0.010 | |
k | 2.706 | 3.841 | 5.024 | 6.635 |
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