1 . 用量词符号表述下列命题:
(1)任意一个实数乘以
都等于它的相反数;
(2)对任意实数
,都有
;
(3)有些整数既能被2整除,又能被3整除;
(4)某个四边形不是平行四边形.
(1)任意一个实数乘以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acbc6a613224461ade69362d46550474.png)
(2)对任意实数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbc2b5a6677f3010320cf1e88831901a.png)
(3)有些整数既能被2整除,又能被3整除;
(4)某个四边形不是平行四边形.
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20-21高一·江苏·课后作业
2 . 判断下列命题的真假,并写出其否定.
(1)对任意的x∈R,x2-x-1≤0;
(2)所有能被5整除的整数都是奇数;
(3)对任意的x∈Q,
x2+
x+1是有理数;
(4)有些实数的绝对值是正数;
(5)
x0,y0∈Z,
x0+y0=3.
(1)对任意的x∈R,x2-x-1≤0;
(2)所有能被5整除的整数都是奇数;
(3)对任意的x∈Q,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
(4)有些实数的绝对值是正数;
(5)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/408c3726fe0b0698826dc623f269e179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
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2021高一·江苏·专题练习
3 . 用量词符号“
”、“
”表示下列命题,并判断下列命题的真假.
(1)任意实数
都有,
;
(2)存在实数
,
;
(3)存在一对实数
、
,使
成立;
(4)有理数
的平方仍为有理数;
(5)实数的平方大于
:
(6)有一个实数乘以任意一个实数都等于
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49dac463bbb7375dbf8e2246f9a6f0d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/408c3726fe0b0698826dc623f269e179.png)
(1)任意实数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9490565d4714ffcbadb26fdfca443856.png)
(2)存在实数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a0a82fabdbdb1bde72d990e37994f69.png)
(3)存在一对实数
![](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/1efce6f8aac68204cb626e2358404e04.png)
(4)有理数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(5)实数的平方大于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c95b6be4554f03bf496092f1acdfbb89.png)
(6)有一个实数乘以任意一个实数都等于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c95b6be4554f03bf496092f1acdfbb89.png)
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