Edexcel P4 2024 June — Question 9

Exam BoardEdexcel
ModuleP4 (Pure Mathematics 4)
Year2024
SessionJune
TopicVolumes of Revolution

9. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{e583bf92-d6a9-4f1a-b3c8-372afa6e0a0e-26_543_604_255_733} \captionsetup{labelformat=empty} \caption{Figure 3}
\end{figure} The curve \(C\), shown in Figure 3, has equation $$y = \frac { x ^ { - \frac { 1 } { 4 } } } { \sqrt { 1 + x } ( \arctan \sqrt { x } ) }$$ The region \(R\), shown shaded in Figure 3, is bounded by \(C\), the line with equation \(x = 3\), the \(x\)-axis and the line with equation \(x = \frac { 1 } { 3 }\) The region \(R\) is rotated through \(360 ^ { \circ }\) about the \(x\)-axis to form a solid.
Using the substitution \(\tan u = \sqrt { x }\)
  1. show that the volume \(V\) of the solid formed is given by $$k \int _ { a } ^ { b } \frac { 1 } { u ^ { 2 } } \mathrm {~d} u$$ where \(k , a\) and \(b\) are constants to be found.
  2. Hence, using algebraic integration, find the value of \(V\) in simplest form.