Answer
$y = 2,{\text{ it is a horizontal asymptote}}{\text{}}$
Work Step by Step
$$\eqalign{
& \mathop {\lim }\limits_{x \to - \infty } f\left( x \right) = 2 \cr
& {\text{The statements means that while }}x{\text{ take values to negative}} \cr
& {\text{infinity}}{\text{, the function }}f\left( x \right){\text{ approaches to }}2,{\text{ then}} \cr
& y = 2,{\text{ it is a horizontal asymptote}}{\text{.}} \cr} $$
