Réponse:
Bonsoir
1) (2 × 4x + 2 × (-9) ) - ( 4x × 3x + 4x × 8 - 9 × 3x - 9 × 8)
= ( 8x - 18 ) - ( 12x^2 + 32x - 27x - 72 )
= 8x - 18 - 12x^2 - 32x + 27x + 72
= -12x^2 + 3x + 54
2) -3 (4x - 9) ( x + 2)
3) a) ( 4 × 0 - 9 ) 2 - ( 4 × 0 - 9 ) ( 3 × 0 + 8) = 54
b) ( 4 × 9/4 - 9 ) 2 - (4 × 9/4 - 9 ) (3 × 9/4 + 8) = 0