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Math Help - Subsets that have a disjoint

  1. #1
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    Subsets that have a disjoint

    How can I prove this:
     If A \subset B\cup C and A and B are disjoint, the  A \subset C.
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  2. #2
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    Quote Originally Posted by tigergirl View Post
    How can I prove this:
     If A \subset B\cup C and A and B are disjoint, the  A \subset C.
    If A~\&~B are disjoint then x \in A~ \Rightarrow ~ x\notin B.
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  3. #3
    Member billa's Avatar
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    after you answer your question in your other post, this follows directly from that - just write down the definition of disjoint sets, which is that their intersection is the empty set.
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