More or less. The proper question you should ask is this: "Is the function defined immediately to the left and right of the point where the limit is taken?"

So for example, with your original problem, you might ask yourself: "Is the function defined at \(\displaystyle x=-1.000001\)? Is the function defined at \(\displaystyle x=-0.999999\)?"

If either answer is no, then the limit doesn't exist at that point.

If both answers are yes, it's *possible* that the limit exists, but you need to check further to see if it actually does.

In general, like you concluded, it will work out that any function that contains \(\displaystyle \sqrt{x}\) will not have a limit at any negative number. However consider another example where a function contains \(\displaystyle \sqrt{-x}\) in which case the limit could exist at negative values of x but won't exist at positive values of x! You should make sure you examine what is actually under the radical.