N2021 P2 Q3

N2021 P2 Q3

9 marks
Past Year National Exams
Free
  1. The function \(\mathrm{h}\) is defined by \(\mathrm{h}:x\mapsto \frac{1}{2}{{x}^{2}}+3\), for \(x\in \mathbb{R}\).
    The function \(\mathrm{g}\) is defined by \(\mathrm{g}:x\mapsto \frac{x+1}{5x-1}\), for \(x\in \mathbb{R}\), \(x\ne 0.2\).
    1. Find \(\mathrm{gh}\left( 2 \right)\).[2]
    2. Find the value of \(x\) for which \(\mathrm{g}\left( x \right)=1.4\).[1]
  2. The function \(\mathrm{f}\) is defined by \(\mathrm{f}:x\mapsto \frac{x+a}{2x+b}\), for \(x\in \mathbb{R}\), \(x\ne k\).
    1. Give an expression for \(k\) and explain why this value of \(x\) has to be excluded from the domain of \(\operatorname{f}\).[2]
      The function \(\mathrm{f}\) is such that \(\mathrm{f}\left( x \right)={{\mathrm{f}}^{-1}}\left( x \right)\) for all \(x\) in the domain of \(\mathrm{f}\).
    2. Determine the possible values of \(a\) and of \(b\).[3]
    3. Find an expression for \({{\mathrm{f}}^{-1}}\left( -4 \right)\).[1]

Video Solution:

Default solution

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Answer:\[\dfrac{4-a}{9}\]

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