9.
$$f ( x ) = \frac { ( 3 - 4 \sqrt { } x ) ^ { 2 } } { \sqrt { } x } , \quad x > 0$$
- Show that \(\mathrm { f } ( x ) = 9 x ^ { - \frac { 1 } { 2 } } + A x ^ { \frac { 1 } { 2 } } + B\), where \(A\) and \(B\) are constants to be found.
- Find \(\mathrm { f } ^ { \prime } ( x )\).
- Evaluate \(\mathrm { f } ^ { \prime } ( 9 )\).