olymmath

KZ-MO 2023

Kazakhstan Mathematical Olympiad 2023.

Other problems

Problem 3

a,b,ca,b,c are positive real numbers such that max⁡{a(b+c)a2+bc,b(c+a)b2+ca,c(a+b)c2+ab}≤52\max\{\frac{a(b+c)}{a^2+bc},\frac{b(c+a)}{b^2+ca},\frac{c(a+b)}{c^2+ab}\}\le \frac{5}{2} . Prove inequality a(b+c)a2+bc+b(c+a)b2+ca+c(a+b)c2+ab≤3\frac{a(b+c)}{a^2+bc}+\frac{b(c+a)}{b^2+ca}+\frac{c(a+b)}{c^2+ab}\le 3

Problem 4

Given x,y>0x,y>0 such that x2y2+2x3y=1x^2y^2+2x^3y=1 . Find the minimum value of sum x+yx+y