Solution. Let f(x) = \frac{1}{x}. Then this can be rewritten as
\begin{align*} f(x) = x^{-1}. \end{align*}
\begin{align*} f'(x) = (-1) \cdot x^{-1 - 1} = -x^{-2}. \end{align*}
\begin{align*} f(x) = x^{-1}. \end{align*}
\begin{align*} f'(x) = (-1) \cdot x^{-1 - 1} = -x^{-2}. \end{align*}