解题方法
1 . 已知x为正数,a=-x+
,b=5x-
,用反证法证明:a,b中至少有一个不小于6.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d1751f99590f9539afce484c196f719.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf35027e76f8ea593f82023973d4aba3.png)
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名校
解题方法
2 . (1)已知
,求证:
;
(2)若x,y都是正实数,且
,用反证法证明:
与
中至少有一个成立.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ada798eeba5bd19d497bfd0741afd00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cbc2278547879e9246de7e749a774d7.png)
(2)若x,y都是正实数,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f9e131cdd242d56b6dba05ab3363ef3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e36ffaf917dcebc8719f2ca539a774ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef8e5b510c343f9d3d626fa1a4b36bad.png)
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2020-06-16更新
|
394次组卷
|
4卷引用:河南省洛阳市2019-2020学年高二下学期期中考试数学 (文)试题
3 . (1)已知
,
.求证:
;
(2)在
中,内角
的对边分别为
.若
,用反证法证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6455e38ff53ede2508e4d9cb23f0b86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91a871ef7bf13de3e15489d65b57a3cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b32e1a1c8cb8f9fdab1d90cb9507c97.png)
(2)在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/432d77fe5ad3032d59a237dd94c8a638.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b774018122dfbf609f08bdbe111e2ab4.png)
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4 . 已知非零实数a、b、c两两不相等.证明:三个一元二次方程
,
,
不可能都只有一个实根.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cee197a607d3e7308d9443ff46be9f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd8d1958a5c4045b8f72a9d45c2f5c21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/104367e0096f4284b349c4e5e25a7e6c.png)
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2021-11-19更新
|
228次组卷
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3卷引用:河南省南阳市第一中学校2021-2022学年高二下学期期中模拟考试数学文科试题
名校
5 . 已知
,求证:
(1)
;
(2)
与
至少有一个大于
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a0c4c098615c6bc7e6dcf72e5b5201a.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2c8cc9a7e986e3a05f436dcf94b0053.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2582892eba557b99dbe879efb9754d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8b00099c87d4771161c1eedad1c5f0c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
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6 . 已知函数
.
(1)求
的值;
(2)求证:
,
,
三个数至少有一个不小于2.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e165965f16fa180a49c024f2977df6bc.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a461f87a3e96b374c1a6ecd831c5b11.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf2c267eee6151e1fb721afcec781311.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06edc3a74f24df928700cb03080662ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94afaacb3e423336ae85e7da73333fb9.png)
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7 . 在
中,角A,B,C为
的三个内角.
(1)若
,证明:
为等腰三角形.
(2)若
,用反证法证明:
为直角三角形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4a62158bd25d9c81c928ea42ace2f54.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3c091b46ed16ba51e82ef420a9ba0ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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2022-04-22更新
|
134次组卷
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3卷引用:河南省南阳地区2021-2022学年高二下学期期中热身摸底考试数学(理)试题
8 . (1)用分析法证明:
;
(2)已知
、
,用反证法证明:
和
中至少有一个是非负数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77d8385ac59f2f1e98f706d95fef5629.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dd0914dc4d4c7f75710ff460a286fcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aeb3cfd923d91ed998c24ae5186d915.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c79751e871257c1dc1233926d0a76220.png)
您最近一年使用:0次
9 . 已知二次函数
(
,
)的图像与
轴有两个不同的交点,若
,且
时,
.
(1)用分析法证明:
是函数
的一个零点;
(2)用反证法证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/331d5e308cd5469e0f28a8d75f79903f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cec12441802f71e803efaf2c62ee588.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/920f30b69a2f0634b0ddc39ef2704b81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfcdd49e3b1e34d8cbc870d9ee8a3d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c73a98c1b3504e09bfbe0db849b0d24.png)
(1)用分析法证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2c70fcaa661df4fbcad820b439accda.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
(2)用反证法证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba97c4b3f44b25cebe765aeb4358cfe6.png)
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2023-03-13更新
|
58次组卷
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2卷引用:陕西省渭南市韩城市新蕾中学2020-2021学年高二下学期第二次月考文科数学试题
10 . 已知二次函数
,证明:
(1)
;
(2)
、
、
中至少有一个不小于
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ea2fdda67d2a98caafce60658a57c15.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33e62a7fe38809bd670fb6696953bbfc.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97912e861c1ce318ca4ef6fbbf59c0d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1a4d3d9fbd097d75114a4a4afa7ea6e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4997b69c21fe0b9baf86d14d1a998da9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
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2022-03-27更新
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136次组卷
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2卷引用:陕西省咸阳市武功县普集高中2021-2022学年高二下学期第一次月考理科数学试题