1 . (1)求证:
;
(2)已知在
中,
是
的中点,证明:
;
(3)已知
,
,且
与
不共线,当
为何值时,向量
与
互相垂直?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2052b9d309f07cf3b9544f09a2223b71.png)
(2)已知在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e1a5884f5abdf9d72561b7a591eda65.png)
(3)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6316d995f00623f05fc3d56a6cbe5f00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/407538138dd68ab917925c2063cc98e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a2f4b1178f68bd147d1a2a6acd04435.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c94075193c11fe43f2396cff5a485054.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9441846da0868582298cece138bec3e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bff01c3e3b53271c5d16ad4e02a930ad.png)
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2 . 用反证法证明命题:“已知
,求证
,
,
中至少有一个大于30”时,要做的假设是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/051cbc93fb80a37d5edee35e928226a1.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/071a7e733d466949ac935b4b8ee8d183.png)
A.![]() ![]() ![]() ![]() | B.![]() ![]() ![]() ![]() |
C.![]() ![]() ![]() ![]() | D.![]() ![]() ![]() ![]() |
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名校
3 . 用反证法证明命题:“已知
,求证a,b,c中至少有一个大于30”时,要做的假设是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/051cbc93fb80a37d5edee35e928226a1.png)
A.a,b,c都大于30 | B.a,b,c至多有一个大于30 |
C.a,b,c不都大于30 | D.a,b,c都不大于30 |
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2022-05-16更新
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3卷引用:河南省驻马店市环际大联考“逐梦计划”2021-2022学年高二下学期期中考试数学(文科)试题
4 . 请选择适当的方法证明下列结论:
(1)求证:
;
(2)已知
,求证:
.
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0c1d583e670dac4530bd57ac9118740.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a0c4c098615c6bc7e6dcf72e5b5201a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6e10cc5dd849caccce37fe98a26c598.png)
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2022-04-02更新
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4卷引用:河南省洛阳市强基联盟2021-2022学年高二下学期大联考数学(文)试题
解题方法
5 . 求证:夹在两个平行平面间的平行线段相等.画图,并用图中字母写出已知、求证;写出证明过程.
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2022-07-05更新
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2卷引用:河南省许昌市2021-2022学年高一下学期期末数学理科试题
名校
6 . (1)证明:若
,则
;
(2)已知
,求证:
,
,
不能同时大于
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e71f9936d51596dfa7a1eb3fbaa00b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69b28c716d53e72489c55897f632f310.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6045d6fcdd88fc44709357ae02da5c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c76aac012a59970e1a00e6a55a354ada.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/622035ccb4b1d5f64d0efeb6e8d1f6db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79834eca6e3145265514c9e6959952e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56d266a04f3dc7483eddbc26c5e487db.png)
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7 . 按要求证明下列命题:
(1)(用分析法证明)已知:
是不相等的正数,求证:
;
(2)(用数学归纳法证明)
(
).
(1)(用分析法证明)已知:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632244ea6931507f8656e1cc3437d392.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98941347dd7ac01f5e63a6c5930dd5fa.png)
(2)(用数学归纳法证明)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b256115e3b54ef332792fa167cc43bc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cea4ac187cbb465180e89f38250b3970.png)
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2021-09-03更新
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3卷引用:河南省实验中学2021-2022学年高二(下)期中数学(理科)试题
河南省实验中学2021-2022学年高二(下)期中数学(理科)试题陕西省宝鸡市金台区2020-2021学年高二下学期期中理科数学试题(已下线)4.4 数学归纳法(课堂培优)-2021-2022学年高二数学课后培优练(苏教版2019选择性必修第一册)
8 . 请阅读下列材料:若两个正实数
,
,满足
,求证:
.
证明:构造函数![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9b23c9166bb905415c1268005f6d6f8.png)
,因为对一切实数
,恒有
,所以
,即
,所以
.
根据上述证明方法,若
个正实数
,
,
,
,满足
,你能得到的结论是( )
![](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/4008e47c0a1cbdf408aee7aa3b146786.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a29e9984ad7ac338129d8672a5b3d1.png)
证明:构造函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9b23c9166bb905415c1268005f6d6f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc174079c25a8631cc86c35bf48dcd62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/babc2bdb59e9ae1821bd48e7395474d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/247b3879c34962c1b9aa2421a47a6004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/17189d13389ae711457906ceb3658baa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a29e9984ad7ac338129d8672a5b3d1.png)
根据上述证明方法,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71e45ab9253fef6c71bfc5f6c9b116b9.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/daa5e9bd516f6282483b92cfe6074623.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c23563a7fd23559de3008713ab5dd47a.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
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2021-03-25更新
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3卷引用:河南省2020-2021学年高二年级阶段性测试(三)理科数学试题
名校
9 . 在用反证法证明命题“已知
,
,且
.求证:
,
中至少有一个小于4”时,假设正确的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67ca5fd57c2c2fcc3c7a574fdd1467d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf5bdf35ee10ceb6d33502a9851b5719.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7efb2989ebf5f9016fcf49b72cce5ac2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0987dee32b383422b1b426c041457f18.png)
A.假设![]() ![]() ![]() | B.假设![]() ![]() ![]() |
C.假设![]() ![]() ![]() | D.假设![]() ![]() ![]() |
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2021-06-23更新
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3卷引用:河南省郑州市2020-2021学年高二下学期期末数学文科试题
10 . (1)设
,用综合法证明:
.
(2)设
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ada798eeba5bd19d497bfd0741afd00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99a737185eb85ca24cf66409ce1e09bc.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1caa2030ac2f57deccc5b24e940facc9.png)
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2021-04-02更新
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3卷引用:河南省南阳市2021-2022学年高二下学期期中质量评估数学(理)试题