SE-SKOLORNAS 2008 Problem 3

The function $f(x)$ has the property that $\frac{f(x)}{x}$ is increasing for $x>0$ . Show that $f(x)+f(y) \leq f(x+y) , \text{for all } x,y>0$

Dataset text AI-MO AoPS. Quoted with source.

Solutions

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