# Functional Equation or Limit?

Calculus Level 3

This problem is taken from Moldova National Mathematics Olympiad, 2013.

Let $$f:(0,+\infty)\rightarrow(0,+\infty)$$ be differentiable and let $$F$$ be a primitive of $$f$$, such that $2(F(x)-f(x))=f^2(x),\forall x\in(0,+\infty).$

Find $$\displaystyle\lim_{x\to+\infty}\dfrac{f(x)}{x}$$.

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