L’Hopitals Rule
Explanation
http://www.math.hmc.edu/calculus/tutorials/lhopital/
http://www.math.oregonstate.edu/home/programs/undergrad/CalculusQuestStudyGuides/SandS/lHopital/
Fun practice quiz
http://www.cdeep.iitb.ac.in/nptel/Core%20Science/Mathematics%20I/Slide/Quiz-20.2.html
Practice video & quiz
http://education-portal.com/academy/lesson/applying-lhopitals-rule-in-complex-cases.html#les