5: Limit at −∞:

(If you do not see where the minus came from, check out the appropriate example in box substitution in Functions - Methods Survey - Limits.)
No horizontal asymptote at −∞, but a chance for oblique.

Oblique asymptote y = −x at −∞.

Limit at ∞:

No horizontal asymptote at ∞, but a chance for oblique.

Oblique asymptote y = x at ∞.

Answer