2010 ACJC CT2

2010 ACJC CT2

11 marks
Mid Year Exam
  1. Given the functions
    \(\mathrm{f}:x\mapsto 3{{x}^{3}}-4{{x}^{2}}-1\), \(x\ge 1\),
    \(\mathrm{g}:x\mapsto {{\mathrm{e}}^{2-0.25{{x}^{2}}}}\), \(x\ge -3\).
    1. Explain why the functions \({{\mathrm{f}}^{-1}}\) and \(\mathrm{gf}\) exist,[2]
    2. Find the exact value of \({{\mathrm{f}}^{-1}}\left( -1 \right)\),[2]
    3. Find the range of \(\mathrm{gf}\), giving your answer in exact form.[2]
  2. The functions \(\mathrm{f}\) and \(\mathrm{h}\) are defined by
    \(\mathrm{f}:x\mapsto {{x}^{2}}-{{\lambda }^{2}}\), \(x\le -\lambda \),
    \(\mathrm{h}:x\mapsto \sqrt{x+{{\lambda }^{2}}}\), \(x\ge 0\).
    where \(\lambda >0\). Define the following functions
    1. \({{\mathrm{f}}^{-1}}\).
    2. \(\mathrm{hf}\).[5]

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Answer:\(R_{gf} = (0, e^2]\); \(f^{-1}: x \mapsto -\sqrt{x + \lambda^2}\); \(hf: x \mapsto x\)

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