21-22高一·湖南·课后作业
1 . 写出下列命题的否定,并判断其真假.
(1)
:若
三条边的长分别为5,12,13,则
是直角三角形;
(2)
:面积相等的三角形都是全等三角形;
(3)
:一元二次方程至多有两个解;
(4)
:若
,则
或
.
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
(3)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
(4)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5873c01192b7d33b7483f444f90b5b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34715101c66fa12ce6baf0a9c53f1672.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb45f673c56a289ea78831c9237e8d20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2a7df955fc17e92fd86302f8c34664a.png)
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2 . 已知条件p:
,条件q:
,则![](https://img.xkw.com/dksih/QBM/2015/3/17/1572008073027584/1572008078721024/STEM/16dfba6a3651448b96f970308785bba1.png)
![](https://img.xkw.com/dksih/QBM/2015/3/17/1572008073027584/1572008078721024/STEM/519873a04dca408c9725dacbea53f12a.png)
![](https://img.xkw.com/dksih/QBM/2015/3/17/1572008073027584/1572008078721024/STEM/ae1f2cebe4934f6aa6e56bd1312fc45d.png)
![](https://img.xkw.com/dksih/QBM/2015/3/17/1572008073027584/1572008078721024/STEM/16dfba6a3651448b96f970308785bba1.png)
A.充分而不必要条件 | B.必要而不充分条件 |
C.充要条件 | D.既不充分也不必要条件 |
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