Réponse :
Explications étape par étape
A = 3x² - 9x + 6
⇔ A = 3x² - 6x - 3x + 6
⇔ A = 3x ( x - 2 ) - 3 ( x - 2 )
⇔ A = ( x - 2 ) ( 3x - 3 )
B = 3 ( x + 1 ) + 3x
⇔ B = 3x + 3 + 3x
⇔ B = 6x + 3
⇔ B = 3 ( 2x + 1 )
C = 2 (x + 6) + 5 (x + 6)
⇔ C = 7 . ( x + 6 )
D = 3 (2x - 6) - 3
⇔ D = 6x - 21
⇔ D = 3 ( 2x - 7 )
E = (x + 1) (2x + 3) + (3 x - 5) (x + 1)
⇔ E = (x + 1) [ (2x + 3) + (3 x - 5) ]
⇔ E = (x + 1) ( 5x - 2 )
F = (5x - 21) (2x + 7) - 3 (5x – 21)
⇔ F = (5x – 21) [ (2x + 7) - 3 ]
⇔ F = (5x – 21) ( 2x + 4 )
G = (5x – 21) ( 2x + 4 ) la même que F
H = ( 5x - 1 )² + 10x - 2
⇔ H = 25x² - 10x + 1 + 10x - 2
⇔ H = 25x² - 1 forme a² - b²
⇔ H = ( 5x - 1 ) ( 5x + 1 ) ]
