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O-LevelAdditional MathematicsFunctions4037/21 · May/June 2013 · Q118 Marks

A one-one function f is defined by f(x) = (x - 1)² – 5 for x ≥ k.

  1. (i)State the least value that k can take.[1]
  2. (ii)For this least value of k write down the range of f,[1]
  3. (iii)find f⁻¹(x),[2]
  4. (iv)sketch and label, on the axes below, the graph of y = f(x) and of y = f⁻¹(x), [Figure 11.1][2]
  5. (v)find the value of x for which f(x) = f⁻¹(x).[2]

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Mark scheme

Marking points from the official mark scheme (May/June 2013). The mark or mark type is shown in brackets.

  1. [1] (i) 1
  2. [1] (ii) f > -5
  3. [1] (iii) Method of inverse
  4. [1] (iii) 1 + √x+5
  5. [1] (iv) f: Positive quadratic curve correct range and domain
  6. [1] (iv) f⁻¹: Reflection of f in y = x
  7. [1] (v) Arrange f (x) = x or f⁻¹ (x) = x to 3 term quadratic = 0
  8. [1] (v) 4 only www

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About this question

Topic
Functions, O-Level Additional Mathematics (syllabus 4037). Structured question, 8 marks.
Source
O-Level Additional Mathematics, May/June 2013 Paper 2 Variant 1, question 11.

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