# Countable derivative

Calculus Level 4

$$f: \mathbb{N} \rightarrow \mathbb{R}$$ is defined as

$f(x)=x + x + x +\ldots (x \text{ times})$

Find $$f'(x)$$.

Clarification:
$$f'(x)$$ represents the derivative of $$f(x)$$ with respect to $$x$$.

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