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Math Help - Set Theory Please Check my Work!

  1. #1
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    Set Theory Please Check my Work!

    Hello! These are two questions I am unsure on for my homework.

    Which of these symbols is used to indicate a comparison between two sets?

    Union
    Intersection
    Subset
    Cartesian Product
    Null Space

    Work: I think it's intersection. But I don't know..

    To prove that A ∪ A = A , each of the following steps can be performed ( where U indicates the universal set ).
    A = ( A ∪ A ) ∩ U by the identity law of intersection
    A = ( A ∪ A ) ∩ ( A ∪ A c )by the complement law for union
    A = A ∪ ( A ∩ A c ) by the distributive law of union over intersection

    A = A ∪ ∅ by the complement law for intersection
    A =A by the identity law for union

    True or False.

    Work: False, because the 2 to 3rd set doesnt make sense.

    TIA!
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  2. #2
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    Quote Originally Posted by aeubz View Post
    Hello! These are two questions I am unsure on for my homework.

    Which of these symbols is used to indicate a comparison between two sets?

    Union

    Intersection

    Subset

    Cartesian Product

    Null Space

    Work: I think it's intersection. But I don't know..

    To prove that A ∪ A = A , each of the following steps can be performed ( where U indicates the universal set ).

    A = ( A ∪ A ) ∩ U by the identity law of intersection

    A = ( A ∪ A ) ∩ ( A ∪ A c )by the complement law for union

    A = A ∪ ( A ∩ A c ) by the distributive law of union over intersection

    A = A ∪ ∅ by the complement law for intersection

    A =A by the identity law for union

    True or False.

    Work: False, because the 2 to 3rd set doesnt make sense.

    TIA!
    Frankly I cannot read or understand your question.
    That tells me a lot about your confusion.
    Now, I do not know why you were asked to do this problem.
    But if the question is important to your future, then you should make every effort to present the question in a readable form.
    There are several guides for that. But learning LaTex is the best.
    We have a tutorial for that on the Forum.
    Last edited by mr fantastic; July 23rd 2009 at 06:27 PM.
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