Edexcel P3 2023 October — Question 10

Exam BoardEdexcel
ModuleP3 (Pure Mathematics 3)
Year2023
SessionOctober
TopicChain Rule

  1. In this question you must show all stages of your working. Solutions relying on calculator technology are not acceptable.
A curve \(C\) has equation $$x = \sin ^ { 2 } 4 y \quad 0 \leqslant y \leqslant \frac { \pi } { 8 } \quad 0 \leqslant x \leqslant 1$$ The point \(P\) with \(x\) coordinate \(\frac { 1 } { 4 }\) lies on \(C\)
  1. Find the exact \(y\) coordinate of \(P\)
  2. Find \(\frac { \mathrm { d } x } { \mathrm {~d} y }\)
  3. Hence show that \(\frac { \mathrm { d } y } { \mathrm {~d} x }\) can be written in the form $$\frac { \mathrm { d } y } { \mathrm {~d} x } = \frac { 1 } { \sqrt { q + r ( x + s ) ^ { 2 } } }$$ where \(q , r\) and \(s\) are constants to be found. Using the answer to part (c),
    1. state the \(x\) coordinate of the point where the value of \(\frac { \mathrm { d } y } { \mathrm {~d} x }\) is a minimum,
    2. state the value of \(\frac { \mathrm { d } y } { \mathrm {~d} x }\) at this point.