Khan Academy Static

The meaning of the derivative is not so straightforward when the input space has multiple dimensions. Partial derivatives allow us to handle this by restricting movement in the input space.

6659_Graphical_understanding_of_partial_derivatives.html

6660_Formal_definition_of_partial_derivatives.html

6658_Partial_derivatives_introduction.html

6661_Symmetry_of_second_partial_derivatives.html