Edexcel P4 2021 October — Question 3

Exam BoardEdexcel
ModuleP4 (Pure Mathematics 4)
Year2021
SessionOctober
TopicPartial Fractions
TypePartial fractions then differentiate

3. $$\mathrm { g } ( x ) = \frac { 3 x ^ { 3 } + 8 x ^ { 2 } - 3 x - 6 } { x ( x + 3 ) } \equiv A x + B + \frac { C } { x } + \frac { D } { x + 3 }$$
  1. Find the values of the constants \(A , B , C\) and \(D\). A curve has equation $$y = g ( x ) \quad x > 0$$ Using the answer to part (a),
  2. find \(\mathrm { g } ^ { \prime } ( x )\).
  3. Hence, explain why \(\mathrm { g } ^ { \prime } ( x ) > 3\) for all values of \(x\) in the domain of g .