Bonjour,
D = (x+5)(2x - 3) - 3(4x + 1)
D = x * 2x + x * (-3) + 5 * 2x + 5 * (-3) - 3 * 4x - 3 * 1
D = 2x² -3x + 10x - 15 -12x -3
D = 2x² + 7x - 12x - 15 - 3
D = 2x² - 5x - 18
Méthode 1 :
D = (1+5)(2*1 - 3) - 3(4 * 1 + 1)
D = 1 * 2 + 1 * (-3) + 5 * 2 + 5 * (-3) - 3 * 4 - 3 * 1
D = 2 - 3 + 10 - 15 - 12 - 3
D = - 1 - 5 - 12 - 3
D = - 6 - 15
D = - 21
Méthode 2 :
D = 2x² - 5x - 18
D = 2 *1² - 5 * 1 - 18
D = 2 - 5 -18
D = - 3 - 18
D = - 21
