1 . 已知命题“在整数集中,若x+y是偶数,则x,y都是偶数”,则该命题的否命题为______ .
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2 . 已知命题P是“若实数a、b满足
且
,则
”,则命题P的否命题是________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d33da711e50e96568facb18cef27165.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91a871ef7bf13de3e15489d65b57a3cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65820d0b1ee4d4c9e635e99299af6ae7.png)
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2019-12-01更新
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116次组卷
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2卷引用:上海市金山中学2019-2020学年高一上学期期中数学试题
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3 . 已知一个命题的逆命题是“若
,
,则
,
”,写出原命题的否命题:______ .
![](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/a5d2a320b9ff137ce3632296c4b1d79a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44b12a22ac48dcbc70d95f03371d874f.png)
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2019-11-15更新
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155次组卷
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2卷引用:上海市大同中学2018-2019学年高一上学期10月学情调研数学试题
4 . 写出下面两个的相关命题的逆命题、否命题、逆否命题,并判断它们的真假:
(1)命题:若
,则
.
逆命题:_______________________________________________________( )
逆否命题:_____________________________________________________( )
(2)命题:设
是实数,如果
,那么
有实数根.
否命题:_______________________________________________________( )
逆否命题:_____________________________________________________( )
(1)命题:若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/432d77fe5ad3032d59a237dd94c8a638.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c22b9d08cf536bbb76bce1b0f135772.png)
逆命题:_______________________________________________________( )
逆否命题:_____________________________________________________( )
(2)命题:设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7f5573b30734d65648f61c0a94c98de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4944b18a1daae0480089124e5551107f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/807d62d0b5623b3bd3cb285560bf8436.png)
否命题:_______________________________________________________( )
逆否命题:_____________________________________________________( )
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5 . 下列说法中:
①“若
,则
”的否命题是“若
,则
”;
②“
”是“
”的必要非充分条件;
③“
”是“
或
”的充分非必要条件;
④“
”是“
且
”的充要条件.
其中正确的序号为__________ .
①“若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bad6987e8abfbf07d6a2650483d2a55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b384412acba251d87902ab928902f16.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bad6987e8abfbf07d6a2650483d2a55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e30c903d8f8a05332af0b19e7e40df3.png)
②“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99c6875d552e9fff3c7d655f3a59b166.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bfcffd48bd96e513072d998b69b6629.png)
③“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3056bd950bb55035358d45d1b7d354c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c400a615a16a1662de98dfb4e49d58d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20c925c4283740ce6cc412c1c5f57b0a.png)
④“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c80c89052d44692bfd1e37805035fb5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6455e38ff53ede2508e4d9cb23f0b86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91a871ef7bf13de3e15489d65b57a3cc.png)
其中正确的序号为
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6 . 写出命题:“若
,则
或
”的否命题________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a02c42eb76182a468ec8c3bbd6bc376e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d217c7b12e12e5fb67472452518859ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7925a4d2592cb38bd92cd9d6b4e732b.png)
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2019-11-13更新
|
161次组卷
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2卷引用:上海市比乐中学2018-2019学年高一上学期期中数学试题
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7 . 已知命题:“若
,则关于x的不等式
的解集为空集”,那么它的逆命题,否命题,逆否命题,以及原命题中,假命题的个数是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3596e4d4efb6365332b2f71480b59011.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22f88cc05a19dc10b3efe295820866cb.png)
A.0 | B.2 | C.3 | D.4 |
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2019-11-13更新
|
258次组卷
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2卷引用:上海市实验中学2019-2020学年高一上学期期中质量检测试卷数学试题
8 . 按要求写出下列命题,并判断真假:
(1)命题:“在
中,若
则
”的逆命题;
(2)命题:“若两个数的和为有理数,则这两个数都是有理数.”的否命题;
(3)命题:“若a≠0且b≠0,则ab≠0”的逆否命题;
(4)命题:“a=0或b=0,则a2+b2=0”的逆否命题;
(1)命题:“在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abcb980da8e86b4cfd322616dc84fc6e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce6f337c00a6d4bf1e7580d8888db3d6.png)
(2)命题:“若两个数的和为有理数,则这两个数都是有理数.”的否命题;
(3)命题:“若a≠0且b≠0,则ab≠0”的逆否命题;
(4)命题:“a=0或b=0,则a2+b2=0”的逆否命题;
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9 . 下列结论正确的是( )
A.命题“若![]() ![]() |
B.命题“若![]() ![]() |
C.命题“若![]() ![]() |
D.命题“若![]() ![]() |
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10 . 命题:已知a,b,c,d为实数,若
,
,则
,该命题的否命题为_______
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f22fec5a381ae8aca93d876e54c79de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd031c16a5cbeb1bab9f913d2ad2cfd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eeda5cef4846ef829069fe27f64e34e.png)
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