1 . 下列各题在应用数学归纳法证明的过程中,有没有错误?如果有错误,错在哪里?
(1)求证:当
时,
.
证明:假设当
时,等式成立,即
.
则当
时,左边
=右边.
所以当
时,等式也成立.
由此得出,对任何
,等式
都成立.
(2)用数学归纳法证明等差数列的前n项和公式是
.
证明,①当
时,左边=
,右边
,等式成立.
②假设当
时,等式成立,即
.则当
时,
,
.
上面两式相加并除以2,可得
,
即当
时,等式也成立.
由①②可知,等差数列的前n项和公式是
(1)求证:当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1933b7c3ace69622339353431c519b13.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f57a93680033e45aa7f4226edcdd0d0c.png)
证明:假设当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/769becde4d8d0c1b487c727bd562bb1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0025cda4a1182a9341e28cf021b3d963.png)
则当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63ba21f3d0cfc86d40e2e06446623ce0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7f6974560f10fa3047f2f6bf77bc1ed.png)
所以当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63ba21f3d0cfc86d40e2e06446623ce0.png)
由此得出,对任何
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1933b7c3ace69622339353431c519b13.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f57a93680033e45aa7f4226edcdd0d0c.png)
(2)用数学归纳法证明等差数列的前n项和公式是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba269108f5612e25822bce40eab39a59.png)
证明,①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c87b351f16728b0023fd63678f8103c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5202cc8a5f8259b25ba31346feafcfe1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c4704eff3c92eaa4e6b040c4bbb542b.png)
②假设当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/769becde4d8d0c1b487c727bd562bb1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0915a8cffc2076e75fdda3484e3f5a6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63ba21f3d0cfc86d40e2e06446623ce0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d19930a09d20a1b2497702a0d2211183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de1ca469cabd255b7fbe8179ae8f6630.png)
上面两式相加并除以2,可得
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bff62fdb872da6debad99b36880d61a6.png)
即当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63ba21f3d0cfc86d40e2e06446623ce0.png)
由①②可知,等差数列的前n项和公式是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba269108f5612e25822bce40eab39a59.png)
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2021-02-07更新
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590次组卷
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5卷引用:人教A版(2019) 选择性必修第二册 新高考名师导学 第四章 4.4 数学归纳法
2 . 分析法又称执果索因法.若用分析法证明“设
,且
,求证:
”索的因应是______ .
①
;②
;③
;④
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce613eaa5df46a50174085ef5d1087fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e56f4504e0f80fd031c8b5f41832e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bff6d61a8eaff20b364a9e3235577c69.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/481ee0d1e39e92a4732eea90225eb94c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6e90787c63ca5b5f1a45e0f6e85aaa1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8062c16e427bcf70b7ab5c94e8f25a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e40e5c797b097deb1f9e89bcb3a405f1.png)
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名校
3 . 已知
,求证
的两根的绝对值都小于1,用反证法证明可假设__________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b8cfed3e48c308e325045cb87d7bdbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1146110d4382c714c10de00dd1273b7f.png)
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4 . 分析法又叫执果索因法,若使用分析法证明:“已知a>b>0,求证:
-
<
.”最终的索因应是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d012d124f04963fb72a68af40d5f8f42.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c462d08d75fcc7ccf9c3ecea1972e26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9c632c082ad3e3fd8389b26d0875559.png)
A.![]() | B.![]() | C.1<![]() | D.a-b>0 |
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2019-05-19更新
|
241次组卷
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2卷引用:吉林省蛟河市第一中学校2018-2019高二下学期期中考试数学(理)试题
名校
解题方法
5 . 如图,在底面为菱形的直四棱柱
中,
,
分别是
的中点.
;
(2)求平面
与平面
所成夹角的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/709a9e8bdb91467826fdf8ee31ac63c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b199a99e53d67ff4abf233930961a29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4cf79ee8726310da8faf61f70cfa682.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78fe6d64ca3dd8568a059d4b867d00ca.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a8035fc825a001d7d9a3dacd8271662.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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2024-03-12更新
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1324次组卷
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5卷引用:山东省泰安市2024届高三下学期一轮检测数学试题
山东省泰安市2024届高三下学期一轮检测数学试题上海市宜川中学2024届高三下学期2月开学考试数学试题湖北省天门市天门中学2023-2024学年高二下学期3月月考数学试题(已下线)信息必刷卷04(上海专用)(已下线)专题03 空间向量及其应用全章复习攻略--高二期末考点大串讲(沪教版2020选修)
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解题方法
6 . 如图,在正三棱柱
中, 点 D在边
上,
.
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
(2)如果点E是
的中点, 求证:
平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dc80093eab6bfbba801d92b57d576b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca5dd496ee0c1170ef6dcc48266ee444.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
(2)如果点E是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab35850dbc661ded6456b70767cc6cd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d560542b646924eaf577480ac73281b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ba9e20d667d04bf3ee7f55cc795ce01.png)
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7 . 如图,四边形
是矩形,
平面
.
平面
;
(2)求直线
和直线
所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee7416683bc7f78ccdb6cee223d64849.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3288afb904176a4745aa11ed5f5f3e55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d7c88c481a78a38809b3abfe64c8d7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c09afc70f448545336304333d5b5658b.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
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名校
解题方法
8 . 如图,已知四棱锥
中,底面
是平行四边形,
为侧棱
的中点.
平面
;
(2)若
为侧棱
的中点,求证:
平面
;
(3)设平面
平面
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c2bc5e50b8dfa02601c70822252854a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1ea0adc03fc8ba355dbdac586f4b707.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/466fabcaac59132fea648ff35342ec9d.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06222ee533c2484ab25321a6abbf98cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d923a338dd2d2e29336b42574d38448.png)
(3)设平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9210dbaa21f2f54fe6045e9961731b27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fde7cfb1172e9d79b89f8ec18f1e767.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0cc699a65e140dd4be6195f25c1e85d.png)
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2024-05-08更新
|
5302次组卷
|
8卷引用:福建省三明第一中学2023-2024学年高一下学期期中考试数学试卷
福建省三明第一中学2023-2024学年高一下学期期中考试数学试卷(已下线)6.4.2平面与平面平行-【帮课堂】(北师大版2019必修第二册)江苏省无锡市辅仁高级中学2023-2024学年高一下学期5月月考数学试卷江苏省镇江市实验高级中学2023-2024学年高一下学期5月月考数学试卷(已下线)专题06 立体几何初步解答题热点题型-《期末真题分类汇编》(江苏专用)(已下线)第11章:立体几何初步章末重点题型复习(2)-【帮课堂】(人教B版2019必修第四册)(已下线)必考考点5 立体几何中的位置关系 专题讲解 (期末考试必考的10大核心考点)(已下线)专题07 立体几何初步(1)-期末考点大串讲(人教B版2019必修第四册)
解题方法
9 . 为研究中国工业机器人产量和销量的变化规律,收集得到了
年工业机器人的产量和销量数据,如下表所示.
记
年工业机器人产量的中位数为
,销量的中位数为
.定义产销率为“
”.
(1)从
年中随机取
年,求工业机器人的产销率大于
的概率;
(2)从
年这
年中随机取
年,这
年中有
年工业机器人的产量不小于
,有
年工业机器人的销量不小于
.记
,求
的分布列和数学期望
;
(3)从哪年开始的连续
年中随机取
年,工业机器人的产销率超过
的概率最小.结论不要求证明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8c9ab8d7876fbe1160ed976495d7dce.png)
年份 | |||||||||
产量万台 | |||||||||
销量万台 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8c9ab8d7876fbe1160ed976495d7dce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88541c92761f06f87a4774bcfe2ff0df.png)
(1)从
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8c9ab8d7876fbe1160ed976495d7dce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef9c407a9e79f3612690b9cff43a08e0.png)
(2)从
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b4a24d6356957767542cb75b94f3ef8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8c4c029e552954bd493b49aeab82d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a829fdd8ec0f3b7ede883cf2c3e53b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/678d2b93237d071c6c13e6055fb68497.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d8b9ad2fcfff3dd546c5fdbedfe6238.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c60e1ba1988005e5fbf117f35762ff53.png)
(3)从哪年开始的连续
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d91e07104b699c4012be2d26160976a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65d9d0d66a7f8fc34082cf8c45f64839.png)
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2024高一下·全国·专题练习
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解题方法
10 . 如图,已知四棱锥
的底面ABCD为平行四边形,
分别是棱
的中点,平面CMN与平面PAD交于PE. 求证:
平面
;
(2)
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fbb19cb4eb2d7f3207559eb07355ba2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edcf19a7f0dd0cdf59516ae585025110.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c89b039cb3a43295ae39d5328bf57f7.png)
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