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Relatively prime numbers

  1. Jan 24, 2009 #1
    I stumbled across this question:Suppose that a and b are relatively prime.Prove that ab and a+b are relatively prime.
     
  2. jcsd
  3. Jan 24, 2009 #2

    MathematicalPhysicist

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    Gold Member

    Use the fact that:
    (a+b)/(ab)=1/b+1/a.
    If I say more than this, then you wouldn't have anything to do for yourself.
     
  4. Jan 24, 2009 #3
    Or you could assume that d|ab and prove that then d cant divide a+b (d=/=1).
     
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