Let $f(x) = \begin{cases} -\frac{2}{x+4}, &\text{if}\ x< -4\\ 2 x+12, &\text{if}\ x> -4 \end{cases}$

Calculate the following limits.

$\displaystyle{\lim_{x\to -4^-}f(x)=}$ help (limits) $\displaystyle{\lim_{x\to -4^+}f(x)=}$ help (limits) $\displaystyle{\lim_{x\to -4}f(x)=}$ help (limits)