Check out this topic in the following free, online textbooks:
Implicit Differentiation
Short Explanations: Math BFF
Longer, lecture style:
Crystal Clear Maths Prof. Leonard Calcworkshop.com
L'Hopitals Rule
Short Explanations: Math By Fives
Longer, lecture style: Prof. RobBob
Optimization Problems
Short Explanations: integralCALC
Longer, lecture style: Calcworkshop.com
Related Rates Problems
Short examples: Calcworkshop.com
Longer, lecture style: Prof. RobBob Prof. Leonard
Online Tutorials (including exercises with solutions)
Problem Sets with solutions
Drill problems for finding a derivative by implicit differentiation.
Drill on implicit differentiation and finding the tangent line at a given point.
Drill on finding the derivative and the tangent line to the inverse of a function.
Drill on using differentials to approximate expressions (linear approximation).
Drill on applying L'Hospital's Rule. (Using finite limits)
Drill on applying L'Hospital's Rule. (Using infinite limits)
Drill problems on the use of Newton's Method.
eCalculus.org and UC Davis Math
Problems on applied maxima and minima
Problems on implicit differentiation
Free Worksheets (with solutions)
Free Quizzes (with solutions)