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On a^4+b^4=c^4+d^4=e^5

Source: USAMO 2015, Problem 5

April 29, 2015
Diophantine equationUSAMOnumber theory

Problem Statement

Let aa, bb, cc, dd, ee be distinct positive integers such that a4+b4=c4+d4=e5a^4+b^4=c^4+d^4=e^5. Show that ac+bdac+bd is a composite number.