Question

已知集合A={1,2,3},A∪B={1,2,3,4},则满足条件的集合B有

Answer 1

满足条件的集合B有：

{4}

{4,3}

{4,2}

{4,1}

{4,3,2}

{4,3,1}

{4,2,1}

{4,3,2,1}