X^3 + x^2 - 9x - 9 = 0
x^2 (x + 1) - 9(x + 1) = 0
(x^2 - 9)(x + 1) = 0
x + 1 = 0
x₁ = - 1
x^2 - 9 = 0
x^2 = 9
x₂ = - 3
x₃ = 3
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2x^3 + 8x - x^2 - 4 = 0
2x (x^2 + 4) - 1(x^2 + 4) = 0
(x^2 + 4)(2x - 1) = 0
x^2 + 4 = 0
x^2 = - 4
==> ∅
2x - 1 = 0
2x = 1
x = 0,5
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3x^3 - x^2 + 18x - 6 = 0
x^2 (3x - 1) + 6(3x - 1) = 0
(3x - 1)(x^2 + 6) = 0
x^2 + 6 = 0
x^2 = - 6
x ==> ∅
3x - 1 = 0
3x = 1
x = 1/3