bonjour
f (0)= - 2 et f ( 2) = 6
( 6 + 2 ) / ( 2 - 0 ) = 8/2 = 4 donc a = 4
f (2) = 6
2 * 4 + b = 6
b = 6 - 8 = - 2
f (x) = 4 x - 2
