9 Functions f and g are defined for \(x > 3\) by
$$\begin{aligned}
& \mathrm { f } : x \mapsto \frac { 1 } { x ^ { 2 } - 9 }
& \mathrm {~g} : x \mapsto 2 x - 3
\end{aligned}$$
- Find and simplify an expression for \(\operatorname { gg } ( x )\).
- Find an expression for \(\mathrm { f } ^ { - 1 } ( x )\) and state the domain of \(\mathrm { f } ^ { - 1 }\).
- Solve the equation \(\operatorname { fg } ( x ) = \frac { 1 } { 7 }\).