Exercice 23 :
I = (6x + 4) (3x + 2)
I = 6x * 3x + 6x * 2 + 4 * 3x + 4 * 2
I = 18x² + 12x + 12x + 8
I = 18x² + 24x + 8
J = (3x + 4) (3x + 2)
J = 3x * 3x + 3x * 2 + 4 * 3x + 4 * 2
J = 9x² + 6x + 12x + 8
J = 9x² + 18x + 8
K = (- 5x + 6) (4x - 2)
K = - 5x * 4x - 5x * (- 2) + 6 * 4x + 6 * (- 2)
K = - 20x² + 10x + 24x - 12
K = - 20x² + 34x - 12
J = (2x - 4) (2x - 4)
J = 2x * 2x + 2x * (- 4) - 4 * 2x - 4 * (- 4)
J = 4x² - 8x - 8x + 16
J = 4x² - 16x + 16
Les * désignent "fois".