Bonsoir,
A = (x + 7)(3 - 2x) + (5x - 2)(4x + 1)
A = 3x - 2x² + 21 - 14x + 20x² + 5x - 8x - 2
A = 18x² - 14x + 19
B = (5x - 2)(5x - 8) - (3x - 5)(x + 7)
B = 25x² - 40x - 10x + 16 - (3x² + 21x - 5x - 35)
B = 25x² - 3x² - 50x - 16x + 16 + 35
B = 22x² - 66x + 51
C = (2x + 3)(5x - 8) - (2x - 4)( 5x - 1)
C = 10x² - 16x + 15x - 24 - (10x² - 2x - 20x + 4)
C = 10x² - 10x² - x + 22x - 24 - 4
C = 21x - 28
Bonne soirée.
