\[ f'(a) = \lim_{b \to a} \frac{f(b) - f(a)}{b - a} \]
\(x = c\) is a critical point for the function \(f(x)\) if \(f'(c) = 0\)
## Constant rule \[ \frac{d}{dx}\lbrack cf(x) \rbrack = c f'(x) \]
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