I just realized that the functions domain is:

all R3 except for (0,0,0).

The function isn't defined at that point and so it isn't in its domain.

Does that mean I can simply use the above formula to show that for all (a,b,c) the limit exists? If that's the case then I suppose I would need to show that the limit = 0 for all (a, b, c) correct? The reason is that for anyway I look at the limit at (0,0,0) I appear to be getting that it doesn't exist.