f : R →R, f (x) = 20x+3f : R →R, f (x) = −18xf : R →R, f (x) =0,5- 12xf : R →R, f (x) = −xf : R →R, f (x) = −18f : R →R, f (x) = -2x-9f : R →R, f (x) = −1,5xf : R →R, f (x) = =3,2+1,5xf : R →R, f (x) = 0f : R →R, f (x) = 2f : R →R, f (x) = 2xf : R →R, f (x) = −1,5