设集合A={4,5,7,9},B={3,4,7,8,9},全集U=A∪B,则集合∁U(A∩B)的真子集共有(  ) A.3个 B.6个 C.7个 D.8个

问题描述:

设集合A={4,5,7,9},B={3,4,7,8,9},全集U=A∪B,则集合∁U(A∩B)的真子集共有(  )
A. 3个
B. 6个
C. 7个
D. 8个

∵集合A={4,5,7,9},B={3,4,7,8,9},
∴A∪B={3,4,5,7,8,9},
A∩B={4,7,9}
∴CU(A∩B)={3,5,8}
∴CU(A∩B)的真子集共有23-1=7
故选:C.