2024 NJC Promo Q10

2024 NJC Promo Q10

13 marks
  1. \[\mathrm{f} : x \mapsto \frac{\sqrt{2}(x-2)}{x^2+x-2}, \quad x \in \mathbb{R}, x > 1,\]
    \[\mathrm{g} : x \mapsto \mathrm{e}^{-x}-1, \quad x \in \mathbb{R}.\]
    1. Determine if the composite function \(\mathrm{fg}\) exists.[2]
    2. Find the exact range of \(\mathrm{gf}\).[3]
    3. The domain of \(\mathrm{f}\) is now restricted to \(0 < x < 1\). Find the value of \(\mathrm{g}^{-1}\mathrm{f}^{-1}(2)\).[3]
  2. \[\mathrm{h} : x \mapsto \sqrt{3}(\sin x + \cos x), \quad x \in \mathbb{R}, -\frac{5}{2} \le x \le p,\]
    where \(p\) is a real constant.
    1. Find the largest exact value of \(p\) such that \(\mathrm{h}^{-1}\) exists.[3]
    2. With the value of \(p\) obtained in part (b)(i), find the solution of \(\mathrm{h}\mathrm{h}^{-1}(x) = \mathrm{h}^{-1}\mathrm{h}(x)\), leaving your answer to 3 decimal places.[2]

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