Edexcel Paper 1 2021 October — Question 4

Exam BoardEdexcel
ModulePaper 1 (Paper 1)
Year2021
SessionOctober
TopicFixed Point Iteration

  1. The curve with equation \(y = \mathrm { f } ( x )\) where
$$f ( x ) = x ^ { 2 } + \ln \left( 2 x ^ { 2 } - 4 x + 5 \right)$$ has a single turning point at \(x = \alpha\)
  1. Show that \(\alpha\) is a solution of the equation $$2 x ^ { 3 } - 4 x ^ { 2 } + 7 x - 2 = 0$$ The iterative formula $$x _ { n + 1 } = \frac { 1 } { 7 } \left( 2 + 4 x _ { n } ^ { 2 } - 2 x _ { n } ^ { 3 } \right)$$ is used to find an approximate value for \(\alpha\).
    Starting with \(x _ { 1 } = 0.3\)
  2. calculate, giving each answer to 4 decimal places,
    1. the value of \(x _ { 2 }\)
    2. the value of \(x _ { 4 }\) Using a suitable interval and a suitable function that should be stated,
  3. show that \(\alpha\) is 0.341 to 3 decimal places.