bonjour
18
f (1) = - 1
f ( - 2) = - 7
( - 7 + 1) / ( - 2 - 1 ) = - 6 / - 3 = 2
la fonction est du type ax + b
f (1) = - 1
1 * 2 + b = - 1
→ b = - 1 - 2 = - 3
f(x) = 2 x - 3
f ( -2 ) = - 7
- 2 * 2 - 3 = - 4 - 3 = - 7
2) f ( - 1 )= 1
f ( - 7 ) = - 2
( - 2 - 1 ) : ( - 7 + 1) = - 3 / - 6 = 1/2 = 0.5
f ( -1) = 1
- 1 * 0.5 + b = 1 → b = 1 + 0.5 = 1.5
f( x) = 0.5 x + 1.5
on vérifie : f ( - 7) = - 7 * 0.5 + 1.5 = - 3.5 + 1.5 = - 2
19)
f ( 2) = - 1 et f ( - 1) = 5
( 5 + 1 ) / ( - 1 - 2 ) = 6/-3 = - 2
2 * - 2 + b = - 1 → b = - 1 + 4 = 3
f (x) = - 2 x + 3
on vérifie
f ( - 1 ) = 5
- 1 * - 2 + 3 = 2 + 3 = 5
