bonjour,
f( -2) = - 1 et f ( 3 ) = 2
( 2 + 1) / ( 3 + 2) = 3/5
f(x) est de forme ax + b
- 2 (3/5) + b = - 1
- 6/5 + b = - 1
b = - 1 + 6/5
b = 1/5
f(x) = 3/5 x + 1/5
f( x) = 0
3/5 x + 1/5 = 0
3 x /5 = - 1/5
- 15 x = - 5
x = 5
f ' (x ) = 3/5 donc conclus
f (-1) = - 2/5
f (0) = 1/5 donc conclus
