7. In this question you must show all stages of your working.
Solutions relying on calculator technology are not acceptable.
$$f ( x ) = 2 x - 3 \sqrt { x } - 5 \quad x > 0$$
- Solve the equation
$$f ( x ) = 9$$
- Solve the equation
$$\mathrm { f } ^ { \prime \prime } ( x ) = 6$$