【题文】已知集合A={1,3, },B={1,m},A∪B=A,则m= ( ).A.0或B.0或3 C.1或D.1或3
【题文】已知集合A={1,3, },B={1,m},A∪B=A,则m= ( ).A.0或B.0或3 C.1或D.1或3
题型:难度:来源:
【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 |
答案
【答案】B
解析
【解析】
试题分析:本题中考查子集的等价形式:
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044042-85580.png)
.
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044042-85081.png)
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044042-97564.png)
且
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044043-54339.png)
,∴
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044043-84744.png)
或
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044043-98732.png)
,解得
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044043-57405.png)
,检验得
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044044-33793.png)
或
![](http://img.shitiku.com.cn/uploads/allimg/20200314/20200314044043-84744.png)
,选B
考点:集合的并集与子集的概念.
举一反三
【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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