Exercice 2 :

1) A = 6x + 24

= 6(x+4)

B = -42 + 7y

= 7(-6+y)

2) C = 7(3+x)

= 7*3 + 7*x

= 21 + 7x

D = -3(4-x)

= -3*4 + (-3) * (-x)

= -12 + 3x

Exercice 3 :

1) Par produit en croix, on a

400 m² → 50 kg

1500 m² → ? kg

2) 1 t = 1000 kg

50 kg → 400 m²

1000 kg → ? m²

m²

3) Surface = 5*150 = 750 m²

400 m² → 50 kg

750 m² → ? kg

kg