题目内容
设集合A={x|0<x<9,x是质数},B={x|0<x<9,x∈N},则满足条件A?S⊆B的集合S共有( )个.
| A.7 | B.8 | C.15 | D.16 |
∵集合A={x|0<x<9,x是质数}={2,3,5,7},
B={x|0<x<9,x∈N}={1,2,3,4,5,6,7,8},
又∵集合S满足条件A?S⊆B
∴S={1,2,3,5,7},或S={2,3,4,5,7},或S={2,3,5,6,7或},或S={2,3,5,7,8},
或S={1,2,3,4,5,7},或S={1,2,3,5,6,7},或S={1,2,3,5,7,8},
或S={2,3,4,5,6,7},或S={2,3,4,5,7,8},或S={2,3,5,6,7,8},
或S={1,2,3,4,5,6,7},或S={1,2,3,4,5,7,8},或S={1,2,3,5,6,7,8},
或S={2,3,4,5,6,7,8},或S={1,2,3,4,5,6,7,8},
故满足条件的集合S共有15个
故选C
B={x|0<x<9,x∈N}={1,2,3,4,5,6,7,8},
又∵集合S满足条件A?S⊆B
∴S={1,2,3,5,7},或S={2,3,4,5,7},或S={2,3,5,6,7或},或S={2,3,5,7,8},
或S={1,2,3,4,5,7},或S={1,2,3,5,6,7},或S={1,2,3,5,7,8},
或S={2,3,4,5,6,7},或S={2,3,4,5,7,8},或S={2,3,5,6,7,8},
或S={1,2,3,4,5,6,7},或S={1,2,3,4,5,7,8},或S={1,2,3,5,6,7,8},
或S={2,3,4,5,6,7,8},或S={1,2,3,4,5,6,7,8},
故满足条件的集合S共有15个
故选C
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