Réponse :
Bonsoir
A = (x + 2)(x -3) + (x - 3)
A = (x + 2)(x -3) + (x - 3) × 1
A = (x -3) ( x + 2 + 1)
A = ( x - 3) ( x + 3)
A = x² - 9 car c'est de la forme ( a - b) (a + b) = a² - b²
avec a = x et b = 3
B = (2x - 3)²
B = (2x)² - 2 × 2x × 3 + 3²
B =2²x² - 12x + 9
B = 4x² - 12x + 9
Pour x = 3
A = ( 3 - 3) ( 3 + 3) = 0 × 6 = 0
B = (2(3) - 3)² = (6 -3)² = 3² =9
Pour x = 1,5 = 3/2
A = (3/2)² - 9
A= 9/4 - 9
A = 9/4 - 36/4
A = - 27/4
B = (2(3/2) - 3)²
B = (3 - 3)²
B = 0
