AQA C3 2013 January — Question 5

Exam BoardAQA
ModuleC3 (Core Mathematics 3)
Year2013
SessionJanuary
TopicComposite & Inverse Functions

5 The function f is defined by $$\mathrm { f } ( x ) = \frac { x ^ { 2 } - 4 } { 3 } , \text { for real values of } x , \text { where } \boldsymbol { x } \leqslant \mathbf { 0 }$$
  1. State the range of f.
  2. The inverse of f is \(\mathrm { f } ^ { - 1 }\).
    1. Write down the domain of \(\mathrm { f } ^ { - 1 }\).
    2. Find an expression for \(\mathrm { f } ^ { - 1 } ( x )\).
  3. The function g is defined by $$\mathrm { g } ( x ) = \ln | 3 x - 1 | , \quad \text { for real values of } x , \text { where } x \neq \frac { 1 } { 3 }$$ The curve with equation \(y = \mathrm { g } ( x )\) is sketched below.
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    1. The curve \(y = \mathrm { g } ( x )\) intersects the \(x\)-axis at the origin and at the point \(P\). Find the \(x\)-coordinate of \(P\).
    2. State whether the function \(g\) has an inverse. Give a reason for your answer.
    3. Show that \(\operatorname { gf } ( x ) = \ln \left| x ^ { 2 } - k \right|\), stating the value of the constant \(k\).
    4. Solve the equation \(\mathrm { gf } ( x ) = 0\).