1) A = (5x + 7) (3x - 4)
A = 5x * 3x + 5x * (- 4) + 7 * 3x + 7 * (- 4)
A = 15x² - 20x + 21x - 28
A = 15x² + x - 28
B = 7 (x - 2) + 5 (2x + 1)
B = 7 * x + 7 * (- 2) + 5 * 2x + 5 * 1
B = 7x - 14 + 10x + 5
B = 17x - 9
2) L = 9x + 9y
L = 9 * x + 9 * y
L = 9 (x + y)
M = 7x² - 14x
M = 7 * x * x - 7 * x * 2
M = 7x (x - 2)
N = x² + 6x
N = x * x + 6 * x
N = x (x + 6)
Les * désignent "fois".