9709 P12 - Jun 2020 - Q5
677
The function \(f\) is defined for \(x \in \mathbb{R}\) by
\(f : x \mapsto a - 2x\),
where \(a\) is a constant.
(a) Express \(ff(x)\) and \(f^{-1}(x)\) in terms of \(a\) and \(x\).
(b) Given that \(ff(x) = f^{-1}(x)\), find \(x\) in terms of \(a\).
