Hi, I'm having trouble solving part c of the following question.

Let $\displaystyle w=1+ai$ where a is a real constant.

a.Show that $\displaystyle \left | w^3 \right | =(1+a^2)^{\frac{3}{2}}$

This part I'm fine with as $\displaystyle |w^3|=|w|^3$

b.Find the values of $\displaystyle a$ for which $\displaystyle |w^3|=8$

I get $\displaystyle a=\pm\sqrt{3}$ for this part.

c.Let $\displaystyle p(z)=z^3+bz^2+cz+d$ where $\displaystyle b,\ c $ and $\displaystyle d$ are non-zero real constants. If $\displaystyle p(z)=0$ for $\displaystyle z=w$ and all roots of $\displaystyle p(z)=0$ satisfy $\displaystyle |w^3|=8$, find the values of $\displaystyle b,\ c$ and $\displaystyle d$ and show that these are the only possible values.

Stuck on this part of the question...

Thanks for your help!