shashou95 Bonjour, a. C' = (x² + 1)² - 4x²C' = (x - 1)² (x + 1)²b. D' = (x² - 1)²D' = x^4 - 2x² + 1c. E' = x² + 2x + 1 + (x + 1)(x - 3)E' = 2(x - 1) (x + 1)d. F' = x² - 2x + 1 + 3x(x - 1)F' = (x - 1) (4x - 1)Bon Courage ; )