- #1

tjohn101

- 93

- 0

## Homework Statement

Find all critical numbers of:

g(x)= sqrt(x

^{2}-4)

and

f(x)= (1)/(x

^{2}-9)

## Homework Equations

n/a

## The Attempt at a Solution

1) sqrt(x

^{2}-4)

simplified to x(x-2)(x+2)

^{-1/2}(please check)

and got zeroes as x=0, x=2, x=-2

and I got confused because if you do g(2) and g(-2) it equals zero. For some reason I can't tell if they are defined or undefined. x=0 works, so that is a critical number. The other two are throwing me off.

2) (1)/(x

^{2}-9)

zeroes were x=-3, x=3, x=0. Plugging 3 and -3 back into f(x) gave me undefined, so I'm pretty sure 0 is the only critical number.

If you could please check the second and help with the first that would be great. Thank you