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MathNet 2007-part-01 — 187 problems (EN–VI) Question 153

Math Olympiad Vault · MathNet 2007-part-01 — 187 problems (EN–VI)

Question 153

Find all functions $f: Q^+ \to Q^+$ such that
$$
f(x) + f(y) + 2xyf(xy) = \frac{f(xy)}{f(x+y)}, \qquad \textcircled{1}
$$
Where $Q^+ = \{q \mid q \text{ is a positive rational number}\}$.