bonjour
f ( 0) = 2 et f ( 3 ) = 0
( 0 - 2 ) / ( 3 - 0 ) = - 2 /3
ax = - 2 x /3
f (3) = 0
3 * - 2/3 + b = 0
b = 6/3 = 2
f (x) = - 2 x /3 + 2
