1) A = (2x + 1) (x-3) + (2x + 1) (3x + 2)
A = (2x aucarré - 6x + x - 3) + 6x aucarré + 4x + 3x + 2)
A = 2x aucarré - 5x - 3 + 6x aucarré + 7x + 2
A = 8x aucarré + 2x - 1
2) A = (2x + 1) (x-3) + (2x + 1) (3x + 2)
A = (2x + 1) (x - 3 + 3x + 2)
A = (2x + 1) (4x - 1)
3) A = 0 alors soit
2x + 1 = 0
2x = -1
x = -1/2
Soit
4x - 1 = 0
4x = 1
x = 1/4
