bonjour
f ( 9) = 2
f ( -1) = environ 1.2
f ( x) = 1
f ( 6) = 1 pourquoi 0.6 ?
f ( - 3 ) = - 2
f ( - 3 ) = - 2 et f ( 9 ) = 2
( 2 + 2 ) / ( 9 + 3 ) = 4/12 = 1/3
ax = x /3
f ( - 3) = - 2
- 3 * 1/3 + b = - 2
- 1 + b = - 2
b = - 2 + 1 = - 1
donc f (x) = x /3 - 1
d'où f ( 9) = 9 * 1/3 - 1 = 3 - 1 = 2
f ( - 1 ) = - 1 * 1/3 - 1 = - 1 /3 - 3/3 = - 4/3
