AQA FP1 2015 June — Question 3

Exam BoardAQA
ModuleFP1 (Further Pure Mathematics 1)
Year2015
SessionJune
TopicRoots of polynomials

3
  1. Show that \(( 2 + \mathrm { i } ) ^ { 3 }\) can be expressed in the form \(2 + b \mathrm { i }\), where \(b\) is an integer.
  2. It is given that \(2 + \mathrm { i }\) is a root of the equation $$z ^ { 3 } + p z + q = 0$$ where \(p\) and \(q\) are real numbers.
    1. Show that \(p = - 11\) and find the value of \(q\).
    2. Given that \(2 - \mathrm { i }\) is also a root of \(z ^ { 3 } + p z + q = 0\), find a quadratic factor of \(z ^ { 3 } + p z + q\) with real coefficients.
    3. Find the real root of the equation \(z ^ { 3 } + p z + q = 0\).
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