$f(x)=\frac{x}{x^2+17x+66}$

a$)$ Give the dormain of $f($in interval notation$)$

b$)$ Find the critical numbers of $f($Separate multiple answers by commas.$)$

c$)$ Delermine the intervals on which $f$ is increasing and decreasing.

$f$ is increasing on:

$f$ is decreasing on: and

d$)$ Use the First Derivative Test to determine whether each critical point is a local maximum, minimum, or neither. Local maxima sccur at $x=($Separate mulbile answers by commas.$)$ Locai minima occur at $I=($Separate multiple answers by commas.$)$