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2001 IMO Shortlist Problems/N5

Revision as of 18:59, 20 August 2008 by Minsoens (talk | contribs) (New page: == Problem == Let <math>a > b > c > d</math> be positive integers and suppose that <center><math>ac + bd = (b + d + a - c)(b + d - a + c).</math></center> Prove that <math>ab + cd</math> i...)
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Problem

Let $a > b > c > d$ be positive integers and suppose that

$ac + bd = (b + d + a - c)(b + d - a + c).$

Prove that $ab + cd$ is not prime.

Solution

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Resources

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