Edexcel P4 2024 June — Question 8

Exam BoardEdexcel
ModuleP4 (Pure Mathematics 4)
Year2024
SessionJune
TopicGeneralised Binomial Theorem
TypeSingle unknown from one coefficient condition

8. $$f ( x ) = ( 8 - 3 x ) ^ { \frac { 4 } { 3 } } \quad 0 < x < \frac { 8 } { 3 }$$
  1. Show that the binomial expansion of \(\mathrm { f } ( x )\) in ascending powers of \(x\) up to and including the term in \(x ^ { 3 }\) is $$A - 8 x + \frac { x ^ { 2 } } { 2 } + B x ^ { 3 } + \ldots$$ where \(A\) and \(B\) are constants to be found.
  2. Use proof by contradiction to prove that the curve with equation $$y = 8 + 8 x - \frac { 15 } { 2 } x ^ { 2 }$$ does not intersect the curve with equation $$y = A - 8 x + \frac { x ^ { 2 } } { 2 } + B x ^ { 3 } \quad 0 < x < \frac { 8 } { 3 }$$ where \(A\) and \(B\) are the constants found in part (a).
    (Solutions relying on calculator technology are not acceptable.)