Is this epsilon-delta proof valid? Prove using $\epsilon- \delta$ that $ \displaystyle \lim_{x \to  -4} \frac { x^2 +  6x + 8 }{x + 4}  = - 2 $. 
Here's a proposed proof:

For $\delta \leq 1$, i.e. $ | x + 4 | < 1 $ which guarantees $x < -1 $, one can argue:
$ \left| \dfrac { x^2 +  6x + 8 }{x + 4} + 2 \right| = \left| \dfrac { x^2 + 8x + 16}{x + 4}\right| < \left| \dfrac { x^2 + 8x + 16}{x}\right| < |x^2 + 8x + 16| = |(x+4)^2| = (x+4)^2 \ .   $
Let's require $(x+4)^2 < \epsilon$, which implies $ | x + 4 | < \sqrt \epsilon $. Therefore we have $\delta = \min \{1, \sqrt \epsilon  \}$.

Is it a valid proof or are there any loopholes I'm unaware of? Side-note: I realize there are different -- and perhaps simpler -- ways to prove this, I just want to see if this very approach is valid.

You have $x^2 + 6x + 8 = (x+2)(x + 4).$  Try factoring and canceling.
