Edexcel FP1 2009 January — Question 5

Exam BoardEdexcel
ModuleFP1 (Further Pure Mathematics 1)
Year2009
SessionJanuary
TopicNewton-Raphson method
TypeNewton-Raphson with complex derivative required

5. $$f ( x ) = 3 \sqrt { } x + \frac { 18 } { \sqrt { } x } - 20$$
  1. Show that the equation \(\mathrm { f } ( x ) = 0\) has a root \(\alpha\) in the interval [1.1,1.2].
  2. Find \(\mathrm { f } ^ { \prime } ( x )\).
  3. Using \(x _ { 0 } = 1.1\) as a first approximation to \(\alpha\), apply the Newton-Raphson procedure once to \(\mathrm { f } ( x )\) to find a second approximation to \(\alpha\), giving your answer to 3 significant figures.