1 . “若
,则
或
”的否命题是( )
![](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/ef00713e73b8357cc7900144f5505bc6.png)
A.若![]() ![]() ![]() | B.若![]() ![]() ![]() |
C.若![]() ![]() ![]() | D.若![]() ![]() ![]() |
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2 . 陈述句“
或
”的否定形式是( ).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fde64f4d3c38e43fbdee24eadc4b0dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eec336faee8689281a6f6b465e7fcff9.png)
A.![]() ![]() | B.![]() ![]() |
C.![]() ![]() | D.![]() ![]() |
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3 . 已知
.
(1)若
是
的必要不充分条件,求实数
的范围;
(2)若
是
的必要不充分条件,求实数
的范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bb67b053a005ace5be3e60dca09813d.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ffc1bb9d53a27d484396ad74d6a26e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e26b38e357c7d985656ba7bb3c794a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
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4 . 下面说法正确的有( )个
①
,
②若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dea4bfa6c5cebd0479f7cbfba64c510.png)
,
③命题“若
,则
”的否命题为真命题,
④命题“若
,则
有实根”的逆否命题为真命题.
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d44011b51454a70d56d6da756cdea9c.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/baea4ea1d1b536bc25df037f3664811a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dea4bfa6c5cebd0479f7cbfba64c510.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c72a54f70277b05bad8bca2c44b0cb0f.png)
③命题“若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/199e9b71bddd6f73725518ab2d567b32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ccaa6e503b61e9ae78d8439cba2e328.png)
④命题“若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/347c62b44fae618a37c145b3b5d1f1db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d5707186257494f1fea86066f2778b5.png)
A.1个 | B.2个 | C.3个 | D.4个 |
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5 . 若命题“
”为假命题,则实数
的取值范围是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b17acb01c8f32d285b2669f71358caf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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6 . “
且
”的否定形式为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38f0e9c04402a0ffdaa25c3e3c82c7dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e30c903d8f8a05332af0b19e7e40df3.png)
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7 . 下列四个结论中正确的是( )
A.命题“![]() ![]() ![]() ![]() |
B.命题“若![]() ![]() ![]() ![]() ![]() |
C.命题“若![]() ![]() ![]() ![]() ![]() ![]() |
D.若“![]() ![]() |
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8 . (1)若
或
,则
.写出其逆命题、否命题、逆否命题,并分别指出真假;
(2)设原命题是:当c>0时,若a>b,则ac>bc,写出其逆命题、否命题、逆否命题,并分别指出真假.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a878fd5a7104a7f42770a19097d56457.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6bdfc6e53ec0af4942365bb570c6741.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5dff3ece45bf6c91d9dd8d07ae72584d.png)
(2)设原命题是:当c>0时,若a>b,则ac>bc,写出其逆命题、否命题、逆否命题,并分别指出真假.
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9 . “若
,则
或
”的否命题是( )
![](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/ef00713e73b8357cc7900144f5505bc6.png)
A.若![]() ![]() ![]() | B.若![]() ![]() ![]() |
C.若![]() ![]() ![]() | D.若![]() ![]() ![]() |
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10 . 若命题“若
,则
”为真命题,则下列命题中可能为假命题的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f18de12ff9bd3041309d8f5aa1871d9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dcd99ebc04cf45a291506bcad598d00.png)
A.若![]() ![]() | B.若![]() ![]() |
C.若![]() ![]() | D.若![]() ![]() |
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