x³-3x²-3x+1=0 помогите

X³ - 3 * X² - 3 * X + 1 = (X³ + 1) - (3 * X² + 3 * X) = (X + 1) * (X² - X + 1) - 3 * X * (X + 1) =

(X + 1) * (X² - 4 * X + 1)

X₁ = -1   X₂₃ = 2 ± √ 3