Math Help - Simple "finding the domain" review

1. Simple "finding the domain" review

Technically I'm taking Calculus, but this is still in the range of Algebra I believe.

The question is:

3x+5
over
x^2+9x+20

And all we have to do is state the intervals for the domain. So I have (-INF, -6],[-3,INF).

But it's asking for three intervals, and I'm not sure what to put in the third one.

We're using an online system,, so it's possible it could be a bug I suppose, but if not, I'm not sure what I'm missing.

2. $f(x)=\frac{3x+5}{x^2+9x+20}$

The condition is $x^2+9x+20\neq 0$

$x^2+9x+20=0\Rightarrow x_1=-5, \ x_2=-4$

Then $x\in\mathbb{R}-\{-5,-4\}$

or $x\in(-\infty,-5)\cup(-5,-4)\cup(-4,\infty)$