bonsoir
f ( -2) = 8 et f( 3 ) = - 1
( - 1 - 8 ) / ( 3 + 2 ) = - 9/5
ax = - 9 x /5
f ( - 2 ) = 8
- 2 * - 9/5 + b = 8
18/5 + b = 8
b = 40/5 - 18/5 = 22/5 = 4.4
f (x ) = - 9 x /5 + 4.4
f ( 3 ) = 3 * - 9 /5 + 4.4 = - 27/5 + 4.4 = - 5.4 + 4.4 = - 1
f ( 10) = - 10 * 9/5 + 4.4 = - 90/5 + 4.4 = - 18 + 4.4 = 13.6
coefficient directeur négatif donc fonction décroissante
