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Baltic Way 1995 · Problem 1

Number Theory

Find all triples (x,y,z)(x, y, z) of positive integers satisfying the system of equations

{x2=2(y+z)x6=y6+z6+31(y2+z2)\left\{\begin{array}{l} x^{2}=2(y+z) \\ x^{6}=y^{6}+z^{6}+31\left(y^{2}+z^{2}\right) \end{array}\right.
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Topics

Diophantine equations

Solutions

Solution

Solution: From the first equation it follows that xx is even. The second equation implies x>yx>y and x>zx>z. Hence 4x>2(y+z)=x24x > 2(y+z) = x^{2}, and therefore x=2x=2 and y+z=2y+z=2, so y=z=1y=z=1. It is easy to check that the triple (2,1,1)(2,1,1) satisfies the given system of equations.

Contest context

Results from Baltic Way 1995

9 teams

Mean score
2.2 / 5
Scores of 4 or 5
4 / 9
Estonia
0 / 5

Score distribution

05
10
20
30
40
54
All team scores
TeamScore
Poland5 / 5
Latvia0 / 5
Sweden0 / 5
Lithuania5 / 5
Denmark5 / 5
Finland5 / 5
St. Petersburg0 / 5
Estonia0 / 5
Iceland0 / 5