CAIE P1 2003 November — Question 10

Exam BoardCAIE
ModuleP1 (Pure Mathematics 1)
Year2003
SessionNovember
TopicComposite & Inverse Functions

10 Functions \(f\) and \(g\) are defined by $$\begin{aligned} & \mathrm { f } : x \mapsto 2 x - 5 , \quad x \in \mathbb { R } ,
& \mathrm {~g} : x \mapsto \frac { 4 } { 2 - x } , \quad x \in \mathbb { R } , \quad x \neq 2 . \end{aligned}$$
  1. Find the value of \(x\) for which \(\mathrm { fg } ( x ) = 7\).
  2. Express each of \(\mathrm { f } ^ { - 1 } ( x )\) and \(\mathrm { g } ^ { - 1 } ( x )\) in terms of \(x\).
  3. Show that the equation \(\mathrm { f } ^ { - 1 } ( x ) = \mathrm { g } ^ { - 1 } ( x )\) has no real roots.
  4. Sketch, on a single diagram, the graphs of \(y = \mathrm { f } ( x )\) and \(y = \mathrm { f } ^ { - 1 } ( x )\), making clear the relationship between these two graphs.