4 The functions f and g are defined for all real values of \(x\) by
$$\mathrm { f } ( x ) = 2 x ^ { 3 } + 4 \quad \text { and } \quad \mathrm { g } ( x ) = \sqrt [ 3 ] { x - 10 }$$
- Evaluate \(\mathrm { f } ^ { - 1 } ( - 50 )\).
- Show that \(\operatorname { fg } ( x ) = 2 x - 16\).
- Differentiate \(\operatorname { gf } ( x )\) with respect to \(x\).