Réponse:
a. (5x + 7)(x - 3) - (x - 3) (x + 2) = (x - 3)((5x + 7) - (x + 2)) = (x - 3)(5x + 7 - x - 2) = (x - 3)(4x + 5)
b. (x - 3)(2x - 5) + 2x - 6 = c'est pas possible (ou alors j'y arrive pas)
c. (x - 3) ² + x - 3 = (x - 3)(x - 3) + x - 3 = (x - 3)(x - 3) = (x - 3) ²
d. (x + 3)(x - 3) - 5(x - 3) ² = (x + 3)(x - 3) - 5(x - 3)(x - 3) = (x - 3)((x - 3) - 5(x - 3)) = (x - 3)(x - 3 - 5 - 5x + 15) = (x - 3)(-4x + 7)
