Bonjour ! ;)
Réponse :
Exercice 2 :
I = (x + 1) (x + 5)
I = x * x + x * 5 + 1 * x + 1 * 5
I = x² + 5x + x + 5
I = x² + 6x + 5
J = (4x + 5) (2x + 6)
J = 4x * 2x + 4x * 6 + 5 * 2x + 5 * 6
J = 8x² + 24x + 10x + 30
J = 8x² + 34x + 30
K = (5u + 1) (2 - 3u)
K = 5u * 2 + 5u * (- 3u) + 1 * 2 + 1 * (- 3u)
K = 10u - 15u² + 2 - 3u
K = - 15u² + 7u + 2
L = (- 3 + n) (- 2n - 5)
L = - 3 * (- 2n) - 3 * (- 5) + n * (- 2n) + n * (- 5)
L = 6n + 15 - 2n² - 5n
L = - 2n² + n + 15
