MathDB
a+b+c=0 if unlikely inequalities hold

Source: Baltic Way 1995

October 8, 2011
inequalitiesalgebra proposedalgebra

Problem Statement

The real numbers a,ba,b and cc satisfy the inequalities ab+c,bc+a|a|\ge |b+c|,|b|\ge |c+a| and ca+b|c|\ge |a+b|. Prove that a+b+c=0a+b+c=0.