C'(t) = \frac(3)(t^2 + 4) - 3t(2t)(t^2 + 4)^2 = \frac3t^2 + 12 - 6t^2(t^2 + 4)^2 = \frac-3t^2 + 12(t^2 + 4)^2. - Nelissen Grade advocaten