Réponse :
(3x + 5)(x + 1) + x(6x + 10) = (3x + 5)(x + 1) + x[ 2 . (3x + 5)]
(3x + 5)(x + 1) + x(6x + 10) = (3x + 5)(x + 1) + 2x (3x + 5)
(3x + 5)(x + 1) + x(6x + 10) = (3x + 5)[ (x+1) + 2x]
(3x + 5)(x + 1) + x(6x + 10) = (3x + 5) (x+2x+1)
(3x + 5)(x + 1) + x(6x + 10) = (3x + 5) (3x+1)
