Problem A. 644. (May 2015)

A. 644. Let \(\displaystyle f(x,y)\) be a polynomial with two variables and integer coefficients such that \(\displaystyle f\) is constant neither in \(\displaystyle x\)- nor in \(\displaystyle y\)-direction. Prove that \(\displaystyle \max_{a,b\in[-2,2]}\big|f(a,b)\big|\ge4\).

Based on the idea of Tamás Erdélyi, College Station, Texas

(5 pont)

Deadline expired on June 10, 2015.

Statistics:

1 student sent a solution.
5 points:	Williams Kada.

Problems in Mathematics of KöMaL, May 2015