Réponses

2013-10-05T11:54:03+02:00
(x+1)^2-(2x-6)^2
x * 2x + x * (-6) + 1 * 2x + 1 * (-6) ^2
2x + (-6x) + 2x + (-6) ^2
-2x - 6 ^2
-4x - 36
2013-10-05T12:03:08+02:00
A = (x + 1)² - (2x - 6)²
A = [(x + 1) - (2x - 6)] [(x + 1) + (2x - 6)]
A = (x + 1 - 2x + 6) (x + 1 + 2x - 6)
A = (-x + 7) (3x - 5)

Ici, j'ai utilisé l'identité remarquable a² - b² = (a - b) (a + b).