Local and Global Extrema, 1st and 2nd Derivative and Candidates Tests, Multi-variable - Calculus 3

This video explains the derivative and candidates tests for multi-variable functions to identify critical points, local/relative and global/absolute extrema (maxima and minima) and saddle points, including the horizontal tangent plane, second directional derivative, Hessian and quadratic form for the 2nd derivative test conditions and where it fails, testing of interior and boundary points to identify global extrema, and worked example practice problems.

0:00 Local extrema
7:24 Second derivative test
21:33 Candidates test
29:21 Worked examples