9 A function f is such that \(\mathrm { f } ^ { \prime } ( x ) = 6 ( 2 x - 3 ) ^ { 2 } - 6 x\) for \(x \in \mathbb { R }\).
- Determine the set of values of \(x\) for which \(\mathrm { f } ( x )\) is decreasing.
- Given that \(\mathrm { f } ( 1 ) = - 1\), find \(\mathrm { f } ( x )\).