Directional Derivatives and Tangent Planes

This lecture covers the concept of directional derivatives, the existence of partial derivatives, and the geometric interpretation of tangent planes. It explains how to determine if a function is differentiable at a point and provides examples to illustrate these concepts. The lecture also discusses the conditions for a function to be driftable and the properties of tangent planes. Additionally, it explores the relationship between directional derivatives and tangent planes, emphasizing the importance of understanding these concepts in multivariable calculus.