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1990 IMO Problems/Problem 4

Revision as of 07:44, 19 July 2016 by 1=2 (talk | contribs)

4. Let $\mathbb{Q^+}$ be the set of positive rational numbers. Construct a function $f :\mathbb{Q^+}\rightarrow\mathbb{Q^+}$ such that $f(xf(y)) = \frac{f(x)}{y}$ for all $x, y\in{Q^+}$.

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