AQA Paper 1 2020 June — Question 13

Exam BoardAQA
ModulePaper 1 (Paper 1)
Year2020
SessionJune
TopicComposite & Inverse Functions

13 The function f is defined by $$\mathrm { f } ( x ) = \frac { 2 x + 3 } { x - 2 } \quad x \in \mathbb { R } , x \neq 2$$ 13
    1. Find f-1
      13
  1. (ii) Write down an expression for \(\mathrm { ff } ( x )\).
    13
  2. The function g is defined by $$g ( x ) = \frac { 2 x ^ { 2 } - 5 x } { 2 } \quad x \in \mathbb { R } , 0 \leq x \leq 4$$ 13
    1. Find the range of g .
      13
  3. (ii) Determine whether g has an inverse.
    Fully justify your answer.
  4. Show that $$g f ( x ) = \frac { 48 + 29 x - 2 x ^ { 2 } } { 2 x ^ { 2 } - 8 x + 8 }$$ 13
  5. It can be shown that fg is given by $$f g ( x ) = \frac { 4 x ^ { 2 } - 10 x + 6 } { 2 x ^ { 2 } - 5 x - 4 }$$ with domain \(\{ x \in \mathbb { R } : 0 \leq x \leq 4 , x \neq a \}\)
    Find the value of \(a\).
    Fully justify your answer.