# How do you find the critical numbers of 1/(t^2+3)?

The on;y critical number is $0$.
$f \left(t\right) = \frac{1}{{t}^{2} + 3}$
$f ' \left(t\right) = \frac{- 2 t}{{t}^{2} + 3} ^ 2$
$f ' \left(t\right)$ is never undefined and is $0$ only at $t = 0$