9231 P13 - Jun 2016 - Q8 - 10 marks
6335
The cubic equation
\(z^{3}-z^{2}-z-5=0\)
has roots \(\alpha, \beta\) and \(\gamma\). Show that the value of \(\alpha^{3}+\beta^{3}+\gamma^{3}\) is 19 .
Find the value of \(\alpha^{4}+\beta^{4}+\gamma^{4}\).
Show that the cubic equation with roots \(\frac{\alpha-1}{\alpha}, \frac{\beta-1}{\beta}\) and \(\frac{\gamma-1}{\gamma}\) may be found using the substitution \(z=\frac{1}{1-x}\), and find this equation, giving your answer in the form \(p x^{3}+q x^{2}+r x+s=0\), where \(p, q, r\) and \(s\) are constants to be determined.
