bonjour
f (2) = - 2 et f (3) = - 3
( -3 + 2 ) / ( 3 - 2 ) = - 1 /1 = - 1
donc ax = - x
f ( 2) = - 2
2 * - 1 + b = - 2
b = - 2 + 2 = 0
f (x) = - x + 0
f ( 3) = - 3 *1 + 0 = - 3
ordonnée à l'origine = 0
