4
\includegraphics[max width=\textwidth, alt={}, center]{28beb431-45d5-4300-88fe-00d05d78790b-05_787_892_267_568} The diagram shows the graph of \(y = \mathrm { f } ( x )\), where $$f ( x ) = \begin{cases} 4 - 4 x , & x \leqslant a ,
\ln ( b x - 8 ) - 2 , & x \geqslant a . \end{cases}$$ The range of f is \(\mathrm { f } ( x ) \geqslant - 2\).

1. Show that \(a = \frac { 3 } { 2 }\).
2. Find the value of \(b\).
3. Find the exact value of \(\mathrm { ff } ( - 1 )\).
4. Explain why the function f does not have an inverse.