Edexcel P2 2020 October — Question 3

Exam BoardEdexcel
ModuleP2 (Pure Mathematics 2)
Year2020
SessionOctober
TopicFactor & Remainder Theorem
TypeOne factor, one non-zero remainder

3. $$f ( x ) = a x ^ { 3 } - x ^ { 2 } + b x + 4$$ where \(a\) and \(b\) are constants. When \(\mathrm { f } ( x )\) is divided by ( \(x + 4\) ), the remainder is - 108
  1. Use the remainder theorem to show that $$16 a + b = 24$$ Given also that ( \(2 x - 1\) ) is a factor of \(\mathrm { f } ( x )\),
  2. find the value of \(a\) and the value of \(b\).
  3. Find \(\mathrm { f } ^ { \prime } ( x )\).
  4. Hence find the exact coordinates of the stationary points of the curve with equation \(y = \mathrm { f } ( x )\).
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