Explications étape par étape :
B (mal recopié)
A = 3 x (2x + 4)
⇔ A = 6x² + 12x
E = ( 3x + x ) ( 3x + 4 )
⇔ E = 9x² + 12x + 3x² + 4x
⇔ E = 12x² + 16x
F = (-2x + 1)(x - 1)
⇔ F = -2x² + 2x + x - 1
⇔ F = -2x² + 3x - 1
C = x + ( 2x - 1 ) x²
⇔ C = x + 2x³ - x²
⇔ C = 2x³ - x² + x
D = x [-1 + 2 (x + 1) ]
⇔ D = x ( -1 + 2x + 2 )
⇔ D = -x + 2x² + 2x
⇔ D = 2x² + x
G = ( 5x - 2 ) ( 3x - 1 ) - ( x + 1 ) × 2
⇔ G = 15x² - 5x - 6x + 2 - 2x - 2
⇔ G = 15x² - 13x
