摘要:已知全集U={1,2,3,4,5},集合A={x|x2-3x+2=0},B={x|x=2a,a∈A},则集合中元素的个数为( ) A.1 B.2 C.3 D.4 解析:由题意,知A={1,2},B={2,4}, ∴A∪B={1,2,4}. ∴={3,5}. 答案:B
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已知全集U={1,2,3,4,5,6,7,8},M={1,3,5,7},
N={5,6,7},则
(M∪N)=( )
A.{5,7} B.{2,4}
C.{2,4,8} D.{1,3,5,6,7}
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