Math and science::Analysis::Tao::10: Differentiation of functions
Derivative of monotone functions
Monotone increasing implies [...]
Let \( X \) be a subset of \( \mathbb{R} \), and let \( x_0 \in X \) be a limit point of \( X \). Let \( f: X \to \mathbb{R} \) be a function. If \( f \) is [...] and is [...], then \( f'(x_0) \ge 0 \).
If instead, \( f \) is monotone decreasing, then \( f'(x_0) \le 0 \).