bonjour
f ( 3) = 2 et f ( 10 ) = - 6
( - 6 - 2 ) / ( 10 - 3 ) = - 8 /7
ax = - 8 x / 7
f ( 3 ) = 2
3 * - 8/7 + b = 2
- 24/7 + b = 2
b = 2 + 24/7 = ( 14 + 24) / 7 = 38/7
f (x) = - 8 x / 7 + 38/7
d'où f( 10 ) = - 80/7 + 38/7 = - 42/7 = - 6
tu as la fonction donc tu peux faire