Bonjour ! ;)
Réponse :
Exercice 5 :
A = (x + 1) (x + 4)
A = x * x + x * 4 + 1 * x + 1 * 4
A = x² + 4x + x + 4
A = x² + 5x + 4
B = (x + 1) (4 - x)
B = x * 4 + x * (- x) + 1 * 4 + 1 * (- x)
B = 4x - x² + 4 - x
B = - x² + 3x + 4
C = (x - 1) (4 + x)
C = x * 4 + x * x - 1 * 4 - 1 * x
C = 4x + x² - 4 - x
C = x² + 3x - 4
D = (x - 1) (x - 4)
D = x * x + x * (- 4) - 1 * x - 1 * (- 4)
D = x² - 4x - x + 4
D = x² - 5x + 4
