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USAMO 2014 — Days 1 and 2 Question 2

USAMO · USAMO 2014 — Days 1 and 2

Question 2

Find all functions $f:\mathbb Z\to\mathbb Z$ satisfying
$$xf(2f(y)-x)+y^2f(2x-f(y))=\frac{f(x)^2}{x}+f(yf(y))$$
for every pair of integers $x,y$ with $x\ne0$.

Proposed by Titu Andreescu (as credited in the supplied compilation).