CAIE P1 2020 June — Question 9

Exam BoardCAIE
ModuleP1 (Pure Mathematics 1)
Year2020
SessionJune
TopicComposite & Inverse Functions

9 The functions f and g are defined by $$\begin{aligned} & \mathrm { f } ( x ) = x ^ { 2 } - 4 x + 3 \text { for } x > c , \text { where } c \text { is a constant, }
& \mathrm { g } ( x ) = \frac { 1 } { x + 1 } \quad \text { for } x > - 1 \end{aligned}$$
  1. Express \(\mathrm { f } ( x )\) in the form \(( x - a ) ^ { 2 } + b\).
    It is given that f is a one-one function.
  2. State the smallest possible value of \(c\).
    It is now given that \(c = 5\).
  3. Find an expression for \(\mathrm { f } ^ { - 1 } ( x )\) and state the domain of \(\mathrm { f } ^ { - 1 }\).
  4. Find an expression for \(\mathrm { gf } ( x )\) and state the range of gf .