Svp l'exercice 4 avec justification merci

Bonjour

Soit f (x) = - 4x + 8

a. f (x) = - 4x + 8

f (- 3) = - 4 * - 3 + 8 = 12 + 8 = 20

b. - 4x + 8 = - 20

- 4x = - 20 - 8

- 4x = - 28

x = 28/4

x = 7

c. f (4) = - 4 * 4 + 8 = - 16 + 8 = - 8

d. - 4x + 8 = - 28

- 4x = - 28 - 8

- 4x = - 36

x = 36/4

x = 9.