Find All Valid Real Roots for the Equation $$x ^ { 6 } + 56 x ^ { 3 } - 512 = 0$$

Multiple Choice

Find all valid real roots for the equation.
- $$x ^ { 6 } + 56 x ^ { 3 } - 512 = 0$$

A) $x = 2 , x = - 4$
B) $x = - 2 , x = 4$
C) $x = 2 , x = 4$
D) $x = - 2 , x = - 4$