6 The function f is defined by \(\mathrm { f } ( x ) = 2 x ^ { 2 } - 16 x + 23\) for \(x < 3\).
- Express \(\mathrm { f } ( x )\) in the form \(2 ( x + a ) ^ { 2 } + b\).
- Find the range of f.
- Find an expression for \(\mathrm { f } ^ { - 1 } ( x )\).
The function g is defined by \(\mathrm { g } ( x ) = 2 x + 4\) for \(x < - 1\). - Find and simplify an expression for \(\mathrm { fg } ( x )\).