Bonsoir.
J'imagine que O = 0 (zéro)
A= 1 × a + a × a = a² + a
B = a × a × a - 0 x b = [tex]a^{3}[/tex]
C = 6 × а × а - а - a = 6a² - 2a = 2a × (3a - 1)
D = 2 × a × 3 × a = 6a²
E = a × a × b × 3 = 3a²b
F = 1 × a × a × b × 0 = 0
G = a × 2 × b × a × b = 2a²b²
H = (a + b)(a + b) = a² + ab + ba + b² = a² + 2ab + b² = (a + b)²
Bonne soirée à toi :)