2025 VJC P1 Q2

2025 VJC P1 Q2

8 marks

The function \(\mathrm{f}\) is defined by

\[\mathrm{f} : x \mapsto \frac{x-1}{x}, x \in \mathbb{R}, x \neq 0, x \neq 1\]

  1. Show that \(\mathrm{f}^2(x) = \mathrm{f}^{-1}(x)\).[3]
  2. Find \(\mathrm{f}^3(x)\) in simplified form.[1]
  3. Find \(\mathrm{f}^{2030}(5)\).[2]

Functions \(\mathrm{g}\) and \(\mathrm{h}\) are defined by

\[\mathrm{g} : x \mapsto \frac{x-1}{x}, x \in \mathbb{R}, x \geq 1\]

\[\mathrm{h} : x \mapsto -\sin ax, x \in \mathbb{R}\]

where \(a\) is a positive constant.

  1. Find the value of \(a\) given that the range of \(\mathrm{hg}\) is \((-1, 0]\).[2]

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Answer:(a) \(\mathrm f^{-1}(x)=\mathrm f^2(x)=\dfrac{1}{1-x}\) (b) \(\mathrm f^3(x)=x\) (c) \(-\dfrac14\) (d) \(a=\dfrac\pi2\)

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