F (X) = (2 * X² - 3 * X + 3) / (X + 1) = (2 * X² - 3 * X - 5 + 8) / (X + 1) = 2 * X - 5 + 8 / (X + 1) F '(X) = 2 - 8 / (X + 1)² F ' (X) = 0 ⇒ (X + 1)² = 4 ⇒ X₁ = -3 , X₂ = 1