AQA FP2 2008 January — Question 4

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

4 The cubic equation $$z ^ { 3 } + \mathrm { i } z ^ { 2 } + 3 z - ( 1 + \mathrm { i } ) = 0$$ has roots \(\alpha , \beta\) and \(\gamma\).
  1. Write down the value of:
    1. \(\alpha + \beta + \gamma\);
    2. \(\alpha \beta + \beta \gamma + \gamma \alpha\);
    3. \(\alpha \beta \gamma\).
  2. Find the value of:
    1. \(\alpha ^ { 2 } + \beta ^ { 2 } + \gamma ^ { 2 }\);
    2. \(\alpha ^ { 2 } \beta ^ { 2 } + \beta ^ { 2 } \gamma ^ { 2 } + \gamma ^ { 2 } \alpha ^ { 2 }\);
    3. \(\alpha ^ { 2 } \beta ^ { 2 } \gamma ^ { 2 }\).
  3. Hence write down a cubic equation whose roots are \(\alpha ^ { 2 } , \beta ^ { 2 }\) and \(\gamma ^ { 2 }\).