MathDB
Easy algebra

Source: III Caucasus Mathematical Olympiad

March 17, 2018
algebra

Problem Statement

Let aa, bb, cc be real numbers, not all of them are equal. Prove that a+b+c=0a+b+c=0 if and only if a2+ab+b2=b2+bc+c2=c2+ca+a2a^2+ab+b^2=b^2+bc+c^2=c^2+ca+a^2.