CAIE P3 2015 November — Question 4

Exam BoardCAIE
ModuleP3 (Pure Mathematics 3)
Year2015
SessionNovember
TopicFixed Point Iteration

4 The equation \(x ^ { 3 } - x ^ { 2 } - 6 = 0\) has one real root, denoted by \(\alpha\).
  1. Find by calculation the pair of consecutive integers between which \(\alpha\) lies.
  2. Show that, if a sequence of values given by the iterative formula $$x _ { n + 1 } = \sqrt { } \left( x _ { n } + \frac { 6 } { x _ { n } } \right)$$ converges, then it converges to \(\alpha\).
  3. Use this iterative formula to determine \(\alpha\) correct to 3 decimal places. Give the result of each iteration to 5 decimal places.