What is L'Hospitals rule?

Question

I'm currently taking ap calc and I need help with some problems but keep seeing L'Hospitals rule brought up. My math teacher didn't teach us that so I'm wondering what it may be.

Answer 1

If a limit is indeterminant, e.g., lim f(x) / g(x) = 0 / 0 or = ∞ / ∞, that limit can be determined by taking the limit of the first derivative, e.g, lim f'(x) / g'(x)

The index in you text book should list L'Hospital's Rule with a page number.