MathDB
Three numbers among 1400 given numbers have certain property

Source: 2021 Iran second round mathematical Olympiad P5

May 16, 2021
combinatoricsalgebrainequalitiesIran

Problem Statement

1400 real numbers are given. Prove that one can choose three of them like x,y,zx,y,z such that : (xy)(yz)(zx)x4+y4+z4+1<0.009\left|\frac{(x-y)(y-z)(z-x)}{x^4+y^4+z^4+1}\right| < 0.009