Are Relatively Prime Numbers Always Coprime?

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bhavinsinh

I stumbled across this question:Suppose that a and b are relatively prime.Prove that ab and a+b are relatively prime.

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MathematicalPhysicist

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.

Kurret

Or you could assume that d|ab and prove that then d can't divide a+b (d=/=1).

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