Réponse :
Bonjour,
A = (a + 5)(a + 7)
= a*a + a*7 + 5*a + 5*7
= a² + 7a + 5a + 35
= a² + 12a + 35
B = (y - 6)(y - 9)
= y² - 9y - 6y + 54
= y² - 15y + 54
C = (4x + 3)(3x - 1)
= 12x² - 4x + 9x - 3
= 12x² + 5x - 3
D = (1 - 2t)(1 - 2t)
= 1 - 2t - 2t + 4t²
= 4t² - 4t + 1