Find all solutions of the equation
x^3+125=0
$\displaystyle x^3+125=x^3+5^3=(x+5)(x^2-5x+25)$
So one root is x=-5.
Now using the quadratic formula we get
$\displaystyle x=\frac{-(-5) \pm \sqrt{(-5)^2-4(1)(25)}}{2(1)}=\frac{5 \pm \sqrt{-75}}{2}=\frac{5 \pm 5i\sqrt{3}}{2}$
Since these are zero's $\displaystyle x-\frac{5 \pm 5i\sqrt{3}}{2}$ are factors.
$\displaystyle \left( x+5 \right) \left(x- \frac{5 + 5i\sqrt{3}}{2}\right) \left( x- \frac{5 - 5i\sqrt{3}}{2}\right) $