9.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{e1a283dd-c30a-45ee-af0c-429791036753-4_549_721_251_390}
\captionsetup{labelformat=empty}
\caption{Figure 1}
\end{figure}
Figure 1 shows the curve with equation \(y = \mathrm { f } ( x )\) which crosses the \(x\)-axis at the origin and at the points \(A\) and \(B\).
Given that
$$f ^ { \prime } ( x ) = 6 - 4 x - 3 x ^ { 2 } ,$$
- find an expression for \(y\) in terms of \(x\),
- show that \(A B = k \sqrt { 7 }\), where \(k\) is an integer to be found.