Caracterize a função inversa

\[\begin{array}{*{20}{c}}
{f\left( x \right) = 6x + 5}&{}&{}&{g\left( x \right) =  – \frac{{12}}{{x + 3}}}
\end{array}\]

Como ${D_f} = D{‘_f} = \mathbb{R}$ e $y = 6x + 5 \Leftrightarrow x = \frac{{y – 5}}{6}$, então: \[\begin{array}{*{20}{l}}
{{f^{ – 1}}:}&{\mathbb{R} \to \mathbb{R}} \\
{}&{x \to \frac{x}{6} – \frac{5}{6}}
\end{array}\]

Como ${D_g} = \mathbb{R}\backslash \left\{ { – 3} \right\}$, $D{‘_g} = \mathbb{R}\backslash \left\{ 0 \right\}$ e $y =  – \frac{{12}}{{x + 3}} \Leftrightarrow x =  – 3 – \frac{{12}}{y}$, então: \[\begin{array}{*{20}{l}}
{{g^{ – 1}}:}&{\mathbb{R}\backslash \left\{ 0 \right\} \to \mathbb{R}} \\
{}&{x \to  – 3 – \frac{{12}}{x}}
\end{array}\]