Cube Roots of Unity
Let x be the cube root of unity, then
x = (1)1/3
x3 = 1
(x − 1)(x2 + x + 1) = 0
x − 1 = 0 and x2 + x + 1 = 0
Cube roots of unity are
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The two complex roots are conjugate to each other.
In an equation with real coefficients, imaginary roots occur in pairs (one root is the conjugate of the other).
Theorem: For any polynomial equation P(x) = 0 with real coefficients, imaginary (complex) roots occur in conjugate pairs.