Edexcel F1 2023 January — Question 3

Exam BoardEdexcel
ModuleF1 (Further Pure Mathematics 1)
Year2023
SessionJanuary
TopicRoots of polynomials

  1. In this question you must show all stages of your working. Solutions relying entirely on calculator technology are not acceptable.
$$\mathrm { f } ( z ) = 4 z ^ { 3 } + p z ^ { 2 } - 24 z + 108$$ where \(p\) is a constant.
Given that - 3 is a root of the equation \(\mathrm { f } ( \mathrm { z } ) = 0\)
  1. determine the value of \(p\)
  2. using algebra, solve \(\mathrm { f } ( \mathrm { z } ) = 0\) completely, giving the roots in simplest form,
  3. determine the modulus of the complex roots of \(\mathrm { f } ( \mathrm { z } ) = 0\)
  4. show the roots of \(\mathrm { f } ( \mathrm { z } ) = 0\) on a single Argand diagram.