Finding \({\mathrm{f}^n}\) where \({n}\) is large Q1

Finding \({\mathrm{f}^n}\) where \({n}\) is large Q1

8 marks

The functions \(\mathrm{f}\) and \(\mathrm{g}\) are defined as follows:

\(\mathrm{f}:x\mapsto \frac{1}{1-x}\), \(x\in \mathbb{R}\), \(x\ne 0\) or \(1\),

\(\mathrm{g}:x\mapsto 1-\frac{1}{x}\), \(x\in \mathbb{R}\), \(x\ne 0\) or \(1\).

It is given that the range of \(\mathrm{g}\) is \(\mathbb{R}\backslash \left\{ 0,1 \right\}\).

  1. Prove that the composite function \(\mathrm{fg}\) exists.[2]
  2. Express \(\mathrm{fg}\) in a similar form and hence describe the relationship between \(\mathrm{f}\) and \(\mathrm{g}\).[3]
  3. Evaluate \({{\mathrm{f}}^{2011}}{{\mathrm{g}}^{1994}}\left( \frac{1}{2} \right)\).[3]

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Answer:(ii) \(\mathrm{fg}:x\mapsto x\), \(x\in \mathbb{R}\), \(x\ne 0\) or \(1\), \(\mathrm{f}\) and \(\mathrm{g}\) are inverse functions (iii) \(-1\)

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