Mathematical and Physical Journal
for High Schools
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Problem A. 450. (March 2008)

A. 450. The function f\colon \mathbb{R}\to \mathbb{R} satisfies the equation f(x+f(y))+f(f(x)+y)=2x+2y. Prove that f(2x)=2f(x) for all real numbers x.

(5 pont)

Deadline expired on April 15, 2008.


Statistics:

10 students sent a solution.
5 points:Korándi Dániel, Kovács 729 Gergely, Lovász László Miklós, Nagy 235 János, Nagy 314 Dániel, Nagy 648 Donát, Slep Cuvar, Szabó 895 Dávid, Tomon István, Wolosz János.

Problems in Mathematics of KöMaL, March 2008