Question

设集合A={1,2},B={1,2,3},C={2,3,4},则(A∩B)∪C等于(   )

A.{1,2,3}                     B.{1,2,4}

C.{2,3,4}                     D.{1,2,3,4}

Answer 1

D

解法一:∵A∩B={1,2}∩{1,2,3}={1,2},

∴(A∩B)∪C={1,2}∪{2,3,4}={1,2,3,4}.

解法二:∵A∩B={1,2}=A,

∴(A∩B)∪C=A∪C={1,2}∪{2,3,4}={1,2,3,4}.