exercice 2 et 3 svp aidez - moi car se chapitre ....

Exercice 2 : 

A = 2 (x + 6)
A = 2 X x + 2 X 6 
A = 2x + 12

B = 3y (5 + 2y)
B = 3y X 5 + 3y X 2y
B = 15y + 6y²

C = - 2x (5 - 3x)
C = - 2x X 5 - 2x X (- 3x)
C = - 10x + 6x²

D = (4 + 2x) (5x + 3)
D = 4 X 5x + 4 X 3 + 2x X 5x + 2x X 3
D = 20x + 12 + 10x² + 6x
D = 10x² + 26x + 12

E = (4 - x) (3 + 2x)
E = 4 X 3 + 4 X 2x - x X 3 - x X 2x
E = 12 + 8x - 3x - 2x²
E = - 2x² + 5x + 12

Exercice 3 : 

1. Pour x = 3 :

A = x² - x
A = 3² - 3
A = 9 - 3 
A = 6

B = (2x + 4) (x - 3)
B = (2 X 3 + 4) (3 - 3)
B = (6 + 4) X 0
B = 10 X 0
B = 0

2. Pour x = - 2 :

A = x² - x
A = - 2² - (- 2)
A = - 4 + 2
A = - 2

B = (2x + 4) (x - 3)
B = [2 X (- 2) + 4] (- 2 - 3)
B = (- 4 + 4) (- 5)
B = 0 X (- 5)
B = 0