# Thread: Interval Notation Of An Irregular Graph

1. ## Interval Notation Of An Irregular Graph

I have to put the following function into interval notation. $\displaystyle F(x)=3/(x+5)$ Would the correct answer be $\displaystyle Domain=(-\infty,\infty)$ $\displaystyle Range=(-\infty,-3]\cup[3,\infty)$

2. Originally Posted by Mp5xm8
I have to put the following function into interval notation. $\displaystyle F(x)=3/(x+5)$ Would the correct answer be $\displaystyle Domain=(-\infty,\infty)$ $\displaystyle Range=(-\infty,-3]\cup[3,\infty)$
That's not quite right....

What happens to $\displaystyle F(x)$ if $\displaystyle x=-5$ is in the Domain?

Also, as x goes to $\displaystyle \pm\infty$, $\displaystyle F(x)$ goes to zero (but never equals zero!).

Can you take into account these two things and tell us what the domain and range should be?

3. Hmm so i should add a union for the domain as well making it:

$\displaystyle Domain=[3,\infty)\cup(-\infty,-3]$

I'm not sure what to do with your second statement.

4. Originally Posted by Mp5xm8
Hmm so i should add a union for the domain as well making it:

$\displaystyle Domain=[3,\infty)\cup(-\infty,-3]$

I'm not sure what to do with your second statement.
The Domain is all the values of x that are valid for the equation. What values of x are NOT valid for this equation? When you figure that out, you will know what the Domain is. I'll give you a hint. Chris already told you.

Also, if you do ever have to write an interval like the one you did (which is not the right answer for this particular problem), it's customary to have the negative infinity come first, so it would look like :
$\displaystyle (-\infty,-3]\cup[3,\infty)$