N2017 P2 Q3

N2017 P2 Q3

12 marks
Past Year National Exams
Free
  1. The curve \(y=\mathrm{f}(x)\) cuts the axes at \((a,0)\) and \((0,b)\). It is given that \({{\mathrm{f}}^{-1}}(x)\) exists. State, if it is possible to do so, the coordinates of the points where the following curves cut the axes.
    1. \(y=\mathrm{f}(2x)\)
    2. \(y=\mathrm{f}(x-1)\)
    3. \(y=\mathrm{f}(2x-1)\)
    4. \(y={{\mathrm{f}}^{-1}}(x)\)[4]
  2. The function \(\mathrm{g}\) is defined by
    \(\mathrm{g}:x\mapsto 1-\frac{1}{1-x}\), where \(x\in \mathbb{R}\), \(x\ne a\).
    1. State the value of \(a\) and explain why this value has to be excluded from the domain of \(\mathrm{g}\).[2]
    2. Find \({{\mathrm{g}}^{2}}(x)\) and \({{\mathrm{g}}^{-1}}(x)\), giving your answers in simplified form.[4]
    3. Find the values of \(b\) such that \({{\mathrm{g}}^{2}}(b)={{\mathrm{g}}^{-1}}(b)\).[2]

Video Solution:

Default solution

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Answer:Transformations: (i) \((0,b)\), \((\frac a2,0)\); (ii) \((a+1,0)\); (iii) \((\frac12,b)\), \((\frac{a+1}{2},0)\); (iv) \((0,a)\), \((b,0)\). For \(g\): \(a=1\), \(g^2(x)=x\), \(g^{-1}(x)=1-\frac1{1-x}\), \(b=0\text{ or}\hspace{0.5em}2\)

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