设U={1,2,3,4,5,6,7,8},A={3,4,5},B={4,7,8}.求:
(1)?∪A
(2)?∪B
(3)?∪A∩?∪B.
解:由U={1,2,3,4,5,6,7,8},A={3,4,5},B={4,7,8}.
所以(1)?∪A={1,2,6,7,8};
(2)?∪B={1,2,3,5,6};
(3)?∪A∩?∪B={1,2,6,7,8}∩{1,2,3,5,6}={1,2,6}.
分析:直接利用补集与交集的概念进行求解运算.
点评:本题考查了交、并、补集的混合运算,是基础的概念题,属会考题型.