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Set A consisted of all even natural numbers

  1. Feb 14, 2004 #1
    If set A consisted of all even natural numbers (i.e. 2, 4, 6...) and set B consisted of all odd natural numbers (i.e. 1, 3, 5...), then what is the result set of:

    A intersection B

    Would it just be the empty set since no two natural numbers can be even and odd?
  2. jcsd
  3. Feb 14, 2004 #2


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    Yes, exactly. An element is in "A intersect B" if and only if it is in both A and B. There is no integer that is "both" even and odd and so, in this case, A intersect B is empty. That's a very common occurence. In fact there's a special name for it: the two sets are "disjoint".
  4. Feb 14, 2004 #3
    Yes it should be null set
  5. Feb 14, 2004 #4
    I was kind of nervous when I was taking a test on this material because the question was to list at least three elements that were in the following sets, and one of those following sets was A intersection B. Guess it had to be a typo on the test. Hopefully I didn't read the question wrong. If I remember right, I'm very sure that A and B were natural number sets. Ah well.

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