MathDB
3 variable inequality, hard

Source: Korea National 2014 #7

January 21, 2015
inequalitiesinequalities proposed

Problem Statement

Let x,y,zx, y, z be the real numbers that satisfies the following.
(xy)2+(yz)2+(zx)2=8,x3+y3+z3=1(x-y)^2+(y-z)^2+(z-x)^2=8, x^3+y^3+z^3=1
Find the minimum value of x4+y4+z4x^4+y^4+z^4.