Réponse :
bonjour
f (5) = - 3 et f ( - 2 ) = - 2
( - 2 + 3 ) / ( - 2 - 5 ) = - 1/7
ax = - x /7
f ( - 2 ) = - 2
- 2 * - 1/7 + b = - 2
2/7 + b = - 2
b = - 2 - 2/7 = - 14/7 - 2/7 = - 16/7
f (x) = - x /7 - 16/7
d'où f ( 5 ) = 5 * - 1/7 - 16/7 = - 5/7 - 16/7 = - 21/7 = - 3
Explications étape par étape :