First partial derivative f(x,y)=y/(x²+y²) | fx | Video 1

Partial derivatives of a function in three variables f(x,y,z)=xz-4x³y²z³ | ∂f/∂x, ∂f/∂y and ∂f/∂z

Second partial derivative of f(x,y)=y/(x²+y²) | fxy | ∂²f/∂x∂y| Video 3B

A trick to visualize partial derivatives