Explications étape par étape:
1) f(5) = 3-2×5= 3-10= -7
2) f(-4) = 3-2×(-4) = 3-(-8) =3+8= 11
3) f(-3) = 3-2×(-3) = 3-(-6) = 9
4) f(2,5) = 3-2×2,5 = 3-5 = -2
