Arturo O. answered 02/15/20
Experienced Physics Teacher for Physics Tutoring
I would start by factoring it as a sum of cubes.
x3 + 1 = (x + 1)(x2 - x + 1) = 0
You can see from the factor (x + 1) that -1 is a real solution. Now get the two complex solutions from the factor (x2 - x + 1) using the quadratic formula.
x = [1 ± √(-3)]/2
x = (1 ± i√3)/2 = 1/2 ± i[(√3)/2]
|x| = {(1/2)2 + [(√3)/2]2}1/2 = ?
You can finish from here.