Which are cubic functions? Check all that apply.f(x) = –4 – 2x + 5x3f(x) = –3x – 1f(x) = –x2 + 5x – x3f(x) = x2 – 6x3 + 2x4 + 1f(x) = 2x3 + 3x2 – x – 3f(x) = 3x2 – 1 – 8x