The importance of plugging in -2 first is that you can determine if you're dealing with an undetermined form or not, in this case you see you get the undetermined form: .
Now plug in -2 again, so what's the limit?
I want to be clear on this and correct me if I am wrong: if I get an undetermined value when I plug in the value (e.g. -2), then I have to calculate the limit the long way, which is what we just did. Otherwise, if I don't get an undertermined value, then the answer is the limit?
You will either have to use L'Hopital's rule or the substitution u=x+2 and consider the resulting limit as u goes to zero