Réponse :
Explications étape par étape :
a) (3x+1) (2x+4) = 6x² +2x + 12x + 4 = 6x² + 14x +4
b) (2x-1) (-3x+1) = -6x² +3x +2x -1 = -6x² + 5x -1
c) (2-x) (x-2) = 2x -x² -4 + 2x = -x² +4x -4
d) 2 (5x-2) (x+1) = 2( 5x² -2x +5x -2) = 2( 5x² +3x -2) = 10x² +6x -4
e) -(x+1) (x+1) = - (x² +x +x +1) = - (x² +2x +1) = -x² -2x -1
f) (-2x -1) ( -7 -4x) = 14x +7 +8x² +4x = 8x² +18x +7
