Q2 "substitute in negative infinity" -- Seriously? Please never do that. "negative infinity" is NOT a number. Plus, you don't know it the function is continuous. Why are you substituting at all?

Let's assume that as x increases without bound in the negative direction that it eventually decreases below -8. (Why did I bother to say that?)

For x < -8,

Does that do anything for our hunt for the limit?