Edexcel P2 2022 October — Question 2

Exam BoardEdexcel
ModuleP2 (Pure Mathematics 2)
Year2022
SessionOctober
TopicBinomial Theorem (positive integer n)
TypeExpansion up to x^2 term

  1. A curve \(C\) has equation \(y = \mathrm { f } ( x )\) where
$$f ( x ) = ( 2 - k x ) ^ { 5 }$$ and \(k\) is a constant.
Given that when \(\mathrm { f } ( x )\) is divided by \(( 4 x - 5 )\) the remainder is \(\frac { 243 } { 32 }\)
  1. show that \(k = \frac { 2 } { 5 }\)
  2. Find the first three terms, in ascending powers of \(x\), of the binomial expansion of $$\left( 2 - \frac { 2 } { 5 } x \right) ^ { 5 }$$ giving each term in simplest form. Using the solution to part (b) and making your method clear,
  3. find the gradient of \(C\) at the point where \(x = 0\)