How to Change Unacceptable Forms before Using L’Hôpital’s Rule

You can use L’Hôpital’s rule to find a limit for which direct substitution doesn’t work. If substitution produces one of the unacceptable forms, ± ∞ · 0 or ∞ – ∞, you first have to tweak the problem to get an acceptable form before using L’Hôpital’s rule.