Hi there, I'm having trouble with the following question. As usual, I'm probably missing something basic...

If $\displaystyle z=1+\sqrt{3}i$ is a solution to the equation $\displaystyle z^3-a=0,\ a\in\ c$ then the other two solutions are?

I know one of them must be $\displaystyle z=1-\sqrt{3}i$ as the coefficient of $\displaystyle z^3$ is real. But I'm not sure how to find the last solution.

From the options (mc question) it seems that it's either $\displaystyle z=2$ or $\displaystyle z=-2$.

Thanks for your help