A) F : x -----> -3x
F(x) = -3x
> f(-1) = -3(-1)
f(-1) = 3
f(1) = -3(1)
f(1) = -3
f(0) = -3(0)
f(0) = 0
f(4) = -3(4)
f(4) = -12
f(2/3) = -3(2/3)
f(2/3) = -2 [ j'ai simplifié 3 et 3 par 3, reste 1 ]
f(3/2) = -3(3/2)
f(3/2) = -9/2
B) f(x) = -3x
> -3x = 15
x = -15/3
x = -5
-3x = -8
x = 8/3
