【题文】设A={1,4,2x},若B={1,},若BA,则x= &
题型:难度:来源:
【题文】设A={1,4,2x},若B={1,
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044056-87971.png)
},若B
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044057-44600.png)
A,则x= ( )
答案
【答案】C
解析
【解析】
试题分析:因为
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044057-80888.png)
,则
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044057-43729.png)
,或
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044058-45298.png)
,当
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044057-43729.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044058-74033.png)
,但
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044059-82117.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044059-35633.png)
,这与集合的互异性相矛盾, 当
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044058-45298.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044059-87543.png)
,或
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044100-35657.png)
,但
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044100-35657.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044100-97992.png)
,这与集合的互异性相矛盾,综上所述,
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044101-76381.png)
或
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044059-87543.png)
.
考点:集合的性质,集合与集合的关系,考查学生对基本概念的理解,及学生的基本运算能力.
举一反三
【题文】已知集合
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044050-65610.png)
,则
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044050-19079.png)
的所有非空真子集的个数是
【题文】已知集合A={1,3,
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044041-18849.png)
},B={1,m},A∪B=A,则m= ( ).
A.0或![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044042-63654.png) | B.0或3 | C.1或![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044042-63654.png) | D.1或3 |
【题文】已知集合
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044031-75205.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044032-35376.png)
.
(1)求集合
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044032-82279.png)
;
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044032-13347.png)
,求实数
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044033-63961.png)
的取值范围.
【题文】若集合
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044024-50887.png)
则“
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044024-43584.png)
”是“
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044024-94494.png)
”的( )
A.充分不必要条件 | B.必要不充分条件 |
C.充要条件 | D.既不充分也不必要条件 |
【题文】已知集合
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044004-78124.png)
,则
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044005-57475.png)
的所有非空真子集的个数是
.
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