Difference between revisions of "2001 IMO Shortlist Problems/N5"
(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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Revision as of 18:59, 20 August 2008
Problem
Let be positive integers and suppose that
Prove that is not prime.
Solution
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