# An interesting functional equation

Calculus Level 4

Let $$f:\mathbb{R}\rightarrow\mathbb{R}$$ be a continuous function such that

$f(x)-2f\left (\frac{x}{2}\right )+f\left (\frac{x}{4}\right )=x^{2}$

Find $$f(3)-f(0)$$.

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