Ch 4: Introduction to Derivatives Ch 4.1: Derivatives of Powers, Exponentials, and Sums https://youtu.be/zwOOr4cr1voCh 4.2: The Product and Quotient Ruleshttps://youtu.be/Ts8G5SxnhRkCh 4.3/4.4: The Chain Rule (Part 1)https://youtu.be/HJKZTmtmy8MCh 4.3/4.4: The Chain Rule (Part 2)https://youtu.be/0E6k6oOvJ-MCh 4.5: Elasticity of Demandhttps://youtu.be/IP--wG6-OXA