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I Proving Odd and Even

  1. Feb 13, 2016 #1
    How to do this type of problem. I am confused, right now.
    Prove that x-y is even and x2-xy+3 is odd
     
  2. jcsd
  3. Feb 13, 2016 #2

    fresh_42

    Staff: Mentor

    ##7-2=5## is not even and ##7^2 - 7*2 + 3 =38## is not odd.
    However, if ##x-y## is even, then ##x^2 - xy + 3 = x(x-y)+3## is odd.
    Proof: If ##2|(x-y)## then ##2|x(x-y)## and dividing ##x^2 - xy + 3 = x(x-y)+3## by ##2## has a remainder ##1##.
     
  4. Feb 18, 2016 #3

    berkeman

    User Avatar

    Staff: Mentor

    Thread closed for Moderation...
     
  5. Feb 18, 2016 #4

    berkeman

    User Avatar

    Staff: Mentor

    Thread will remain closed. Just a reminder, when you see misplaced schoolwork/homework type questions in the general math forums (especially when the OP shows zero effort to solve the problem), please Report the post rather than responding. Thanks.
     
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