quadruples (maybe posted before)
Source: Austria 1997
July 11, 2009
algebra unsolvedalgebra
Problem Statement
Determine all quadruples of real numbers satisfying the equation:
256a^3 b^3 c^3 d^3\equal{}(a^6\plus{}b^2\plus{}c^2\plus{}d^2)(a^2\plus{}b^6\plus{}c^2\plus{}d^2)(a^2\plus{}b^2\plus{}c^6\plus{}d^2)(a^2\plus{}b^2\plus{}c^2\plus{}d^6).