Conceptual
Login

Evaluating a Derivative Function at a Specified Input

A derivative is itself a function, so $f'$ can be evaluated at any admissible input, and $f'(g(x))$ means the derivative function of $f$ evaluated at the number $g(x)$ rather than the derivative of $f(g(x))$. Covers substituting an expression for the variable inside a derivative and distinguishing 'differentiate then substitute' from 'substitute then differentiate'.