名校
解题方法
1 . 已知
满足三个条件,其中两个条件分别是:
,
.若这样的
恰好有2个,则第三个条件可以是_________ (选出所有符合要求的答案的序号)
①
,②
,③
是等腰三角形,④
是直角三角形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced06b71073e1bb777f326f06016ce17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1cac92e1b66c7c34f5e91d079655048.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a36ec31cfd615abfbee3ed2f4a1d8883.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47d0a801922c34467a5d058ed57d664e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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名校
2 . 已知集合
(
,
),若存在数阵
满足:
①
;
②
.
则称集合
为“好集合”,并称数阵
为
的一个“好数阵”.
(1)已知数阵
是
的一个“好数阵”,试写出
,
,
,
的值;
(2)若集合
为“好集合”,证明:集合
的“好数阵”必有偶数个;
(3)判断
是否为“好集合”.若是,求出满足条件
的所有“好数阵”;若不是,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c7c07bd06408ada63e19cd38444a8a9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd4613271f782a90ab580131d09d03d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5818ede14d21f6df9ef9c2bfe09286c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c5790497e607490f8d6c184f11ad260.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f799bc4317846951767f4aa196bfc105.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54946204c502727ffaee3c0172d195a3.png)
则称集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ddad3d9fdb5e9951b6a1c31f9a72a71.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b68df477b3ee45ac0f725db00d465a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ddad3d9fdb5e9951b6a1c31f9a72a71.png)
(1)已知数阵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e93838d1ac2b07386b69165fe00d9e49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72fa71450b470cb7d6464339873d74b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e81e59019989b7dc2fb59b037ef6e010.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/595044a7750ab4f84519041979c3d780.png)
(2)若集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ddad3d9fdb5e9951b6a1c31f9a72a71.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ddad3d9fdb5e9951b6a1c31f9a72a71.png)
(3)判断
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca1acb90636d27c85b45c0204035594f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7c95469d8d40311c876b3724f032d7e.png)
您最近一年使用:0次
2024-03-27更新
|
1011次组卷
|
4卷引用:北京市日坛中学2023-2024学年高一下学期期中考试数学试题
北京市日坛中学2023-2024学年高一下学期期中考试数学试题北京市丰台区2023-2024学年高三下学期综合练习(一)数学试题北京市第八十中学2023-2024学年高二下学期期中考试数学试题(已下线)压轴题01集合新定义、函数与导数13题型汇总 -1
3 . 如图1,在梯形
中,
,
是线段
上的一点,
,
,将
沿
翻折到
的位置.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/6/211d1e84-85c7-440e-972e-c6d64ffebc7f.png?resizew=616)
(1)如图2,若二面角
为直二面角,
,
分别是
,
的中点,若直线
与平面
所成角为
,
,求平面
与平面
所成锐二面角的余弦值的取值范围;
(2)我们把和两条异面直线都垂直相交的直线叫做两条异面直线的公垂线,点
为线段
的中点,
,
分别在线段
,
上(不包含端点),且
为
,
的公垂线,如图3所示,记四面体
的内切球半径为
,证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10df84d553a8826a7ce9bff4bf0d95b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eb15c7f8fd604976818ff6de254b6a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef0402dd5ae3db10281f9f1e11738bcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cff7399ecc698e2fb415147c96d0d03.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/6/211d1e84-85c7-440e-972e-c6d64ffebc7f.png?resizew=616)
(1)如图2,若二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac9d5946fba71d0623ab27f24c6b57fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07e184efd65dfaa5d62242c482d2158d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0bf12905647aeeded72bbca21a63f319.png)
(2)我们把和两条异面直线都垂直相交的直线叫做两条异面直线的公垂线,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf3834d7ec7531f3c3c0ce9b286f7a49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65bb1c5af4c7a9376882867e07690b18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e42887d9bf31c1dd99f13c39e63c9ab9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65bb1c5af4c7a9376882867e07690b18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4da424b529ab73775b90cd4089d18419.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba57d8c0d92f5b6bede99e8d9d227e40.png)
您最近一年使用:0次
名校
解题方法
4 . 对于一组向量
,
,
,…,
,(
且
),令
,如果存在
,使得
,那么称
是该向量组的“长向量”.
(1)设
,
且
,若
是向量组
,
,
的“长向量”,求实数x的取值范围;
(2)若
,
且
,向量组
,
,
,…,
是否存在“长向量”?给出你的结论并说明理由;
(3)已知
,
,
均是向量组
,
,
的“长向量”,其中
,
.设在平面直角坐标系中有一点列
,
,
,…,
满足,
为坐标原点,
为
的位置向量的终点,且
与
关于点
对称,
与
(
且
)关于点
对称,求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d344174267f996c7cefecfd6985d380.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2e900404ba71110c5861ced9634646f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67dbe2e19d8960789ec873b687998b58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4a47bdc03f0ced8245c526c81593363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd4613271f782a90ab580131d09d03d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bcfc48f9bc23cc43085bdb910e7a136.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92c1d22f02fa7f8f1ff1db3f322a9fc5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e955b4525bb55e72c131d829406df508.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c98c622975aaf93ed0c63be1294d2170.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f50ecfa147131019f969c3bc78169f7.png)
(1)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c33a899454f0d42377d4ea0324dd812.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd4613271f782a90ab580131d09d03d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de8610232c77741a37463feba1a66c94.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67dbe2e19d8960789ec873b687998b58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d344174267f996c7cefecfd6985d380.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2e900404ba71110c5861ced9634646f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67dbe2e19d8960789ec873b687998b58.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74da885934fa5f71f25b65d46346920c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd4613271f782a90ab580131d09d03d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de8610232c77741a37463feba1a66c94.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d344174267f996c7cefecfd6985d380.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2e900404ba71110c5861ced9634646f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67dbe2e19d8960789ec873b687998b58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a164fd6439284f1ff4a9b1f02d609f7.png)
(3)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d344174267f996c7cefecfd6985d380.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2e900404ba71110c5861ced9634646f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67dbe2e19d8960789ec873b687998b58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d344174267f996c7cefecfd6985d380.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2e900404ba71110c5861ced9634646f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67dbe2e19d8960789ec873b687998b58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9112bd58ae60d2516b67de408465ccd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ca270240c9c1d115d3c60b58d1556c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797e67927616b141ed7c6b83f8b6f4fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf83e20035c3afd6d26ebfd53d768a70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82dc7540c4cdee4c34a9311c79b35d95.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fc4dc226800792c55eaa32134041837.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36f306a75051c9a11c92aa30a836a016.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2b5ea93b62e9b06f0060ab0d09e6633.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fc4dc226800792c55eaa32134041837.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e10f2f74e201f77f853e9ed9078615c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f0d68648b10fce54dfc19c5ee60086d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8e57169c0d88ae0b680636653f4c860.png)
您最近一年使用:0次
2024-03-26更新
|
738次组卷
|
6卷引用:上海市建平中学2023-2024学年高一下学期第一次教学质量检测(3月月考)数学试卷
上海市建平中学2023-2024学年高一下学期第一次教学质量检测(3月月考)数学试卷安徽省安庆市第一中学2023-2024学年高一下学期第一次阶段检测数学试题(已下线)模块三专题4大题分类练(专题3 平面向量数量积)【高一下人教B版】(已下线)模块四 专题4 重组综合练(安徽)(已下线)期末测试卷01-《期末真题分类汇编》(上海专用)(已下线)考题猜想03 平面向量-期末考点大串讲(沪教版2020必修二)
5 . 集合
由有限个实数组成,定义集合
的离距
如下:实数轴上,集合
中的每个实数
对应一个点
,实数
对应的点
与所有这些点
的距离的算术平均数记为
,称函数
的最小值为集合
的离距,记为
.例如,集合
的离距是0,集合
的离距是2.
(1)分别求出集合
的离距;
(2)求数集
的离距;
(3)已知非空数集
满足
,试写出一个关于
的大小关系的等式或不等式,并给出证明.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fdb777c90f9cabba8d4ed34c16f4acb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.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/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e51c8010a4568d7d44f261973dea420.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fdb777c90f9cabba8d4ed34c16f4acb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39412925212a989c503e891db840609d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21c6fed9c3cf2c00ba1823c3f0a05615.png)
(1)分别求出集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7384a3e8b9a7ffb00bb124ba97b7c992.png)
(2)求数集
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22accc2928d3370f48a84cc4703a4b07.png)
(3)已知非空数集
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b21e6c4bb62b14f8e70d8f8b1ac911bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3598ab9c4ac9a9496c5f34b9b5fda3cf.png)
您最近一年使用:0次
解题方法
6 . 如图棱长为2的正方体
中,
是
的中点,点
是正方体表面上一动点,点
为
内(不含边界)的一点,若
平面
,则下列说法正确的是( )
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/7/b94f6863-0e63-4295-96b3-75a649185e3b.png?resizew=158)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/394c5d2f55221975503be8aa18022480.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcb49df05f2e31d005735c3f14a21d30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f475878dd1b32b0486cbf7b5ffbedd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c66d99a6a8415ddad22bbed33b64cfb.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/7/b94f6863-0e63-4295-96b3-75a649185e3b.png?resizew=158)
A.平面![]() ![]() ![]() |
B.![]() ![]() ![]() |
C.三棱锥![]() |
D.直线![]() ![]() ![]() |
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7 . 已知函数
,
.
(1)求
;
(2)求函数
在区间
上的最小值;
(3)若函数
,且
的图象与
的图象有3个不同的交点,求实数n的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4c172e201ef1c974d8419303328109b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0df312d3ee83037dd736abb7a14f5ca0.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d0823d52521400037395dd789160b96.png)
(2)求函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61beeaae36eb528269d60d19f391c68b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0de71d25c72850e383a4c841eed0db99.png)
(3)若函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b69f28de04e6340b47f82e84446b83a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7827ea0609176507aa32543f19fdcf9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b3df6647dc0b998afb21fa6b533db58.png)
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名校
8 . 如图所示,在梭长为6的正方体
中,点
是平面
内的动点,满足
,则直线
与平面
所成角的正切值的取值范围为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e975f6c9fafab8fd7639dc0cd0f70a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c74769e4e9f9570aeca28ffd14c168e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c798204bbe306b3efd5bc9eae594c171.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e975f6c9fafab8fd7639dc0cd0f70a4.png)
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2024-03-12更新
|
505次组卷
|
2卷引用:江苏省南京外国语学校2023-2024学年高一下学期5月阶段性测试数学试题
9 . 对于非空集合
,定义其在某一运算(统称乘法)“×”下的代数结构称为“群”
,简记为
.而判断
是否为一个群,需验证以下三点:
1.(封闭性)对于规定的“×”运算,对任意
,都须满足
;
2.(结合律)对于规定的“×”运算,对任意
,都须满足
;
3.(恒等元)存在
,使得对任意
,
;
4.(逆的存在性)对任意
,都存在
,使得
.
记群
所含的元素个数为
,则群
也称作“
阶群”.若群
的“×”运算满足交换律,即对任意
,
,我们称
为一个阿贝尔群(或交换群).
(1)证明:所有实数在普通加法运算下构成群
;
(2)记
为所有模长为1的复数构成的集合,请找出一个合适的“×”运算使得
在该运算下构成一个群
,并说明理由;
(3)所有阶数小于等于四的群
是否都是阿贝尔群?请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38bdb8d4c486c37ac64517ed8d60888b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1240721fdf6d8e1ed9c1158ae723637.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c88c74a9c2efc329f92aa4203f0f780.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c88c74a9c2efc329f92aa4203f0f780.png)
1.(封闭性)对于规定的“×”运算,对任意
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c9cbad1e8b405feac6e8fe403f024b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/830afd1befcf1a92874b5e0bc214578d.png)
2.(结合律)对于规定的“×”运算,对任意
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d4ef2c168b3dba086f2485c3c9cc7c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44d2d88c195317bf5827a1304068f26a.png)
3.(恒等元)存在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25e6faeeed98a19d7012c921ca71a046.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/572f76c63e3a74a90a1e6ca5ae401cf8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96e4c22a6a498e197149ce29d9e98fce.png)
4.(逆的存在性)对任意
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/572f76c63e3a74a90a1e6ca5ae401cf8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5463eaf01a62bc6a772301d9e2ad19c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1487cef1d4227621d9311541dec87156.png)
记群
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c88c74a9c2efc329f92aa4203f0f780.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9f2eb65f2fe6546a5e318343d25fe66.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c88c74a9c2efc329f92aa4203f0f780.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9f2eb65f2fe6546a5e318343d25fe66.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c88c74a9c2efc329f92aa4203f0f780.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d22c891ccf3768b616c5ddaad575aca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8c679fe86736064c65a292db59cb739c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c88c74a9c2efc329f92aa4203f0f780.png)
(1)证明:所有实数在普通加法运算下构成群
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74ba4c1c25324a8875b09d0c855a82ad.png)
(2)记
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d719c0c82f38a886db86c71bbaf8db32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d719c0c82f38a886db86c71bbaf8db32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de4ef5fbf807246591e03d07ba4e3a4e.png)
(3)所有阶数小于等于四的群
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c88c74a9c2efc329f92aa4203f0f780.png)
您最近一年使用:0次
10 . 已知三棱锥
,
面
,
,
交
于
,
交
于
,
,记三棱锥
,四棱锥
的外接球的表面积分别为
,
,当三棱锥
体积最大时,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a39f04d1c3551403dbbed35deb01232.png)
________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdfa54114f04a75b8c96165b3718ed7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4486d52b6e410fd7b60428121d96cef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e7b6d04f024ca05cdfacc8ce9137c15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/212b200cb65843fe03aab377d53991d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c9187c2852c14221b0a0ea0351267ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e0bd63f55069a3bc870915010b39225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/212b200cb65843fe03aab377d53991d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a39f04d1c3551403dbbed35deb01232.png)
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