AQA Paper 1 2021 June — Question 7 2 marks

Exam BoardAQA
ModulePaper 1 (Paper 1)
Year2021
SessionJune
Marks2
TopicSign Change & Interval Methods
TypeRearrange Equation for Iteration

7 The equation \(x ^ { 2 } = x ^ { 3 } + x - 3\) has a single solution, \(x = \alpha\)
7
  1. By considering a suitable change of sign, show that \(\alpha\) lies between 1.5 and 1.6
    [0pt] [2 marks]
    7
  2. Show that the equation \(x ^ { 2 } = x ^ { 3 } + x - 3\) can be rearranged into the form $$x ^ { 2 } = x - 1 + \frac { 3 } { x }$$ 7
  3. Use the iterative formula $$x _ { n + 1 } = \sqrt { x _ { n } - 1 + \frac { 3 } { x _ { n } } }$$ with \(x _ { 1 } = 1.5\), to find \(x _ { 2 } , x _ { 3 }\) and \(x _ { 4 }\), giving your answers to four decimal places.
    7
  4. Hence, deduce an interval of width 0.001 in which \(\alpha\) lies.