27: If you decided to get rid of the square root, you should get

This is not a good idea.

Since the numerator is not an indeterminate difference, a better way seems to be to factor out leading terms and cancel. You should get

It is also possible to use l'Hospital's rule.

Hint on limit at −∞
Hint on limit at 3 from the left
Hint on limit at 3 from the right
Hint on limit at ∞
Answer