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Homework Help: GCD/Number Theory Question

  1. Nov 25, 2007 #1
    Can anyone help me with this?

    If gcd(r,s)=1 then prove that gcd(r^2-s^2, r^2+s^2)=1 or 2.

    i'm so confused.
  2. jcsd
  3. Nov 25, 2007 #2


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    Let p be an odd prime that divides both r^2-s^2 and r^2+s^2. Show that this leads to a contradiction.
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