Réponse:
salut
A(x)= 5x (x + 7)
= 5x × x +5x × 7
= 5x² + 35x
B(x)= (x + 9)(5x + 1)
= x × 5x +x × 1 +9 × 5x +9 × 1
= 5x² +x +45x +9
= 5x² +46x +9
C(x)= (3x - 2)(6x - 4)
= 3x × 6x +3x × (-4) -2 × 6x -2 × (-4)
= 18x² -12x -12x +8
= 18x² -24x +8
Explications étape par étape:
Et voilà,
