Si vous pouvez m aider ça serait parfait merci d avance

Exercice 3 :

G = (2x + 3)(5x - 8) - (2x - 4)(5x - 1)
G = (10x² - 16x + 15x - 24) - (10x² - 2x - 20x + 4)
G = 10x² - 16x + 15x - 24 - 10x² + 2x + 20x - 4
G = 21x - 28

H = (5x - 2)(5x - 8) - (3x - 5)(x + 7)
H = (25x² - 40x - 10x + 16) - (3x² + 21x - 5x - 35)
H = 25x² - 40x - 10x + 16 - 3x² - 21x + 5x + 35
H = 22x² - 66x + 51

I = (x + 7)(3 - 2x) - (5x - 2)(4x + 1)
I = (3x - 2x² + 21 - 14x) - (20x² + 5x - 8x - 2)
I = 3x - 2x² + 21 - 14x - 20x² - 5x + 8x + 2
I = - 22x² - 8x + 23