2024 HCI Promo Q8

2024 HCI Promo Q8

8 marks
Promo

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

\({\mathrm{f}\left( x \right)=\left\{ \begin{matrix} 2-\ln \left( x+\mathrm{e} \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\mathrm{for }\,\,\,\,\,\,-\mathrm{e} < x < 0 \\ \cos \left( \frac{\pi }{2}x \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\mathrm{for }\,\,\,\,\,\,\,\,0\le x\le 1 \\ \end{matrix} \right.}\).

  1. Given that the inverse function \({{\mathrm{f}}^{-1}}\) exists, find the exact value of \(m\) if \({{\mathrm{f}}^{-1}}\left( m \right)=-1\).[2]

Another function \(\mathrm{g}\) is defined by

\(\mathrm{g}\left( x \right)=\sin x\), \(\qquad 0\le x\le \frac{\pi }{4}\).

  1. Explain why the composite function \(\mathrm{fg}\) exists.[2]
  2. Find the exact value of \(\mathrm{fg}\left( \frac{\pi }{6} \right)\).[2]

The domain of \(\mathrm{f}\) is further restricted to \(0\le x\le 1\).

  1. By considering \({{\mathrm{f}}^{2}}\left( 1 \right)\) and \({{\mathrm{f}}^{3}}\left( 1 \right)\), deduce the value(s) of \({{\mathrm{f}}^{n}}\left( 1 \right)\) where \(n\) is a positive integer.[2]

Video Solution:

Video Solution

Video solution locked

A free account saves your progress; this video needs a course plan.

Solution:

Solution locked

680+ questions here come with free worked solutions. A free account saves your questions and progress; this one needs a course plan.

Answer:(a) \({2 - \ln(\mathrm{e} - 1)}\) (b) Since \({\mathrm{R}_{\mathrm{g}} \subseteq \mathrm{D}_{\mathrm{f}}}\). Hence, \({\mathrm{f}\mathrm{g}}\) exists. (c) \({= \frac{1}{\sqrt{2}}}\) (d) \({\mathrm{f}^n(1) = \begin{cases} 0 & \text{if}\hspace{0.5em} n \text{ is odd} \\ 1 & \text{if}\hspace{0.5em} n \text{ is even} \end{cases}}\)

Need help? Join our JC Math tuition classes.

Learn more