Mathematical and Physical Journal
for High Schools
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Problem A. 400. (April 2006)

A. 400. Prove that


\frac{x}{y+2z+3u}+ \frac{y}{z+2u+3x}+ \frac{z}{u+2x+3y} +\frac{u}{x+2y+3z} \ge \frac{2}{3}.

for all real numbers x, y, z, u.

(5 pont)

Deadline expired on May 18, 2006.


Statistics:

13 students sent a solution.
5 points:Blázsik Zoltán, Erdélyi Márton, Estélyi István, Gyenizse Gergő, Hujter Bálint, Jankó Zsuzsanna, Kisfaludi-Bak Sándor, Kónya 495 Gábor, Mészáros Gábor, Nagy 224 Csaba, Paulin Roland, Tomon István, Ureczky Bálint.

Problems in Mathematics of KöMaL, April 2006