If or , where f and g are differentiable and exists, then:
In order to use L'Hôpital's rule, a limit in the form must exist, where a is a number or infinite, and can have the indeterminate forms:
Infinity Minus Infinity
For the indeterminate form of infinity minus infinity, the fractions put themselves into a common denominator.
Zero Times Infinity
The indeterminate form of zero times infinity is transformed as follows:
In the indeterminate forms zero to the power of zero, infinity to the power of zero and one to the power of infinity; make the following transformations: