Bonjour
D = (x - 2,5)²
D = x² - 5x + 6,25
E = (1 - x) (1 + x)
E = 1 - x²
F = (6 + x)²
F = 36 + 12x + x²
G = (x - 3) (x + 3)
G = x² - 9.