2025 SJI P1 Q7

2025 SJI P1 Q7

IB Year 5 | Grade 11
18 marks

Let \(\mathrm f(x)=x^2+1\), where \(x\in\mathbb R\).

  1. The graph of \(y=\mathrm g(x)\) is drawn below.
    1. Find the value of \((\mathrm f\circ\mathrm g)(3)\).
    2. Find the value of \((\mathrm g\circ\mathrm f)(\sqrt2)\).
    3. Sketch the graph of \(y=(\mathrm f\circ\mathrm g)(x)\), showing the coordinates of any intercepts with the axes and the coordinates of the turning points.[9]
  2. If the domain of \(\mathrm f\) is further restricted to \(x\leq k\), state with a reason the largest value of \(k\) for which the function \(\mathrm f^{-1}\) exists. Hence, find \(\mathrm f^{-1}(x)\) and the domain of \(\mathrm f^{-1}\).[6]
  3. Describe a sequence of transformations which transform the graph of \(y=\mathrm f(x)\) to the graph of \(y=3\mathrm f(2x-1)\).[3]

Solution:

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Answer:(a)(i) \(1\), (ii) \(0\), (iii) minima \((0,1),(3,1)\), maximum \((1,17)\). (b) \(k=0,\mathrm f^{-1}(x)=-\sqrt{x-1}\), \(x\geq1\). (c) Horizontal scale \(1/2\), right \(1/2\), vertical scale \(3\).

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