(1)已知
,
,且
,比较是
与
的大小;
(2)用反证法证明:若a、b、
,且
,
,
,则x、y、z中至少有一个不小于0;
(3)用分析法证明:
.
![](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/2958030ec9d7543dda1f529593a915e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a10447baa17b86ca58be2b03197fd55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20d6fc9b90f370fbb27552876b650f8f.png)
(2)用反证法证明:若a、b、
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0097ca400d4619a94c4282c1ef6ec68e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3dbb7a217ab57b67e4b490a948abc575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fdb440c5335d7eec9a9096f34602051.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d5c9678d3ab38dd81558b5885bf76c1.png)
(3)用分析法证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/557d2e3133709e7153c6177a52afc6e3.png)
19-20高一上·山东潍坊·阶段练习 查看更多[3]
山东省潍坊市寿光市现代中学2019-2020学年高一上学期10月月考数学试题(已下线)专题04+常用逻辑用语(2)(反证法)-2020-2021学年新教材高一数学秋季辅导讲义(沪教版2020)(已下线)1.2反证法(第3课时)
更新时间:2019-12-18 15:34:26
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相似题推荐
解答题-证明题
|
适中
(0.65)
解题方法
【推荐1】(1)设
为实数,比较
与
的值的大小.;
(2)若
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632244ea6931507f8656e1cc3437d392.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c925be255ca736a53b24d13ddede1a86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49da63bbdd503faeea1ff9d2df57f83f.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2684b72f9f38f5046c8ecd4280b7b14b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/353a0504082335c98b71653317beabbe.png)
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【推荐2】
,
,
,
为四个互不相等的实数.若A、B、C、D中C最大,求实数a的取值范围,并求出A、B、C、D中最小的数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/149c92f90a37519184e147e443ec826e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a473c4746c7006ee1afc6f36dad3d1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe5039677994d6e20a507aebfba5c58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba391a68cbbbfa9e08538cb1a1dced5f.png)
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解答题-证明题
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【推荐2】证明:(Ⅰ)已知
是正实数,且
.求证:
;
(Ⅱ)已知
,且
,
,
.求证:
中至少有一个是负数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29497c81efb133646bc2aae15a7ecf48.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6a46e678bf9d2df5ad4c782b3dc22f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e943e44d51de25b3e47c62ac7493cbd.png)
(Ⅱ)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f044aa40ee72a2b4932414f78af2a99a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5be97cd1c7111b654d87d8fbb63b6a84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e45d86a588481216a06cb446f78d766.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a08f4e12d723ec259c98b44c5aa1d4a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c27a9af7db04a611063978a7990745e.png)
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解答题-证明题
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【推荐1】用合适的方法证明:
(1)已知
,
都是正数,求证:
.
(2)已知
是整数,
是偶数,求证:
也是偶数.
(1)已知
![](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/2821108f150ed2564cd2d9b55359bfb3.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8cc0b4997cae4d8aec791a1d3923314.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
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【推荐2】解答:
(1)证明:设
都大于0,且
,则
,中至少有一个小于1;
(2)请作一猜想,将上述命题推广到
个数;
(3)请证明(2)中你得出的结论.
(1)证明:设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8639b4896a809224f605e2b3ce8c0b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2034a4f8d6eb4db32cb136ea1301d2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22264525c0b6e5545244be930ce22b35.png)
(2)请作一猜想,将上述命题推广到
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
(3)请证明(2)中你得出的结论.
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