# How do you find the second derivative of f(t)=t^3-4t^2?

Feb 1, 2017

$\frac{{d}^{2} f}{\mathrm{dt}} ^ 2 = 6 t - 8$

#### Explanation:

The power rule states that $\left({x}^{n}\right) ' = n {x}^{n - 1}$. We can use it to find the first derivative:

$\frac{\mathrm{df}}{\mathrm{dt}} = 3 {t}^{2} - 8 t$

We can use the power rule again to find the second derivative.

$\frac{{d}^{2} f}{{\mathrm{dt}}^{2}} = 6 t - 8$.