8th USAMO 1979

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Problem 1

Find all sets of 14 or less fourth powers which sum to 1599.

 

Solution

Answer: none.

The only 4th powers less than 1599 are 1, 16, 81, 256, 625, 1296 (74 = 2401). Note that 1, 81, 625 = 1 mod 16 and 16, 256, 1296 = 0 mod 16. But 1599 = 15 mod 16, so it cannot be expressed as a sum of 14 or less fourth powers.

 


 

8th USAMO 1979

© John Scholes
jscholes@kalva.demon.co.uk
11 May 2002