Number of solutions of equation
Source: 40th Austrian Mathematical Olympiad 2009, round 1, problem 2
August 5, 2009
combinatorics proposedcombinatorics
Problem Statement
How many integer solutions , , , , , , does the equation
2x_0^2\plus{}x_1^2\plus{}x_2^2\plus{}x_3^2\plus{}x_4^2\plus{}x_5^2\plus{}x_6^2\equal{}9
have?