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 :