Aidez moi svp ! Seulement le a-b-c-d merci

Exercice 9 : 

A = (9x - 7)²
A = [(9x)² - 2 X 9x X 7 + 7²]
A = 81x² - 126x + 49

B = (x + 9) (11 - 5x) 
B = x X 11 + x X (- 5x) + 9 X 11 + 9 X (- 5x)
B = 11x - 5x² + 99 - 45x
B = - 5x² - 34x + 99

C = (2x - 3) (2x + 3)
C = (2x)² - 3²
C = 4x² - 9

D = (11 + 8x)²
D = [11² + 2 X 11 X 8x + (8x)²]
D = 64x² + 176x + 121