I'(t) = \frac1000(t^2 + 10) - 1000t(2t)(t^2 + 10)^2 = \frac1000t^2 + 10000 - 2000t^2(t^2 + 10)^2 = \frac-1000t^2 + 10000(t^2 + 10)^2 - Portal da Acústica