Bonjour,
30)
A = (x + 1)²
A = x² + 2x + 1
B = (x + 5) (x - 5)
B = x² - 25
C = (4 - x)²
C = 16 - 8x + x²
C = x² - 8x + 16
31)
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
F = x² + 12x + 36
G = (x - 3) (x + 3)
G = x² - 9