Section 3.4 Chain Rule
The derivative has one more, arguably more fundamental, basic property that is generally referred to as the chain rule.
Theorem 3.4.1. Chain Rule.
If \(g\) is differentiable at \(x\) and \(f\) is differentiable at \(g(x)\text{,}\) then \((f(g(x))'=g'(x)f'(g(x))\)
Let’s try it out.
\begin{equation*}
\begin{array}{llll}
(sin(x^2))' \amp = \amp (x^2)'sin'(x^2) \amp (\text{from the chain rule}) \\
\amp = \amp 2xcos(x^2) \amp (\text{known derivatives}) \\
\end{array}
\end{equation*}