CAIE P3 2007 November — Question 6

Exam BoardCAIE
ModuleP3 (Pure Mathematics 3)
Year2007
SessionNovember
TopicFixed Point Iteration

6
  1. By sketching a suitable pair of graphs, show that the equation $$2 - x = \ln x$$ has only one root.
  2. Verify by calculation that this root lies between 1.4 and 1.7.
  3. Show that this root also satisfies the equation $$x = \frac { 1 } { 3 } ( 4 + x - 2 \ln x )$$
  4. Use the iterative formula $$x _ { n + 1 } = \frac { 1 } { 3 } \left( 4 + x _ { n } - 2 \ln x _ { n } \right)$$ with initial value \(x _ { 1 } = 1.5\), to determine this root correct to 2 decimal places. Give the result of each iteration to 4 decimal places.