\(\mathop {\lim }\limits_{x \to  + \infty } y = \mathop {\lim }\limits_{x \to  - \infty } y\)

\(\mathop {\lim }\limits_{x \to  + \infty } y =  + \infty \)

\(\mathop {\lim }\limits_{x \to  - \infty } y =  + \infty \)       

\(\mathop {\lim }\limits_{x \to  + \infty } y e \mathop {\lim }\limits_{x \to  - \infty } y\)