AQA FP2 2008 June — Question 3

Exam BoardAQA
ModuleFP2 (Further Pure Mathematics 2)
Year2008
SessionJune
TopicRoots of polynomials

3 The cubic equation $$z ^ { 3 } + q z + ( 18 - 12 i ) = 0$$ where \(q\) is a complex number, has roots \(\alpha , \beta\) and \(\gamma\).
  1. Write down the value of:
    1. \(\alpha \beta \gamma\);
    2. \(\alpha + \beta + \gamma\).
  2. Given that \(\beta + \gamma = 2\), find the value of:
    1. \(\alpha\);
    2. \(\quad \beta \gamma\);
    3. \(q\).
  3. Given that \(\beta\) is of the form \(k \mathrm { i }\), where \(k\) is real, find \(\beta\) and \(\gamma\).