Bonjour,
a)
A = - 11x (- 8x + 7)
A = 88x² - 77x
B = (- 6x + 9) (4 - 3x)
B = - 24x + 18x² + 36 - 27x
B = 18x² - 51x + 36
C = (6x + 5)²
C = 36x² + 60x + 25
D = (3x - 1)²
D = 9x² - 6x + 1
E = (7b - 2) (7b + 2)
E = 49b - 4
b)
(5x - 7)² = (5x + 4)²
25x² - 70x + 49 ≠ 25x² + 40x + 16