Question

Mixed Partial Derivative

http://i.imgur.com/6RGXsiB.png

How does the highlighted red area become the highlighted blue area? I understand that (∂/∂y)(∂F/∂x) = (∂²F/∂y∂x) but what do I do with
(∂²F/∂y∂x)(dy/dx)?

Answer 1

dy/dx=-\(F_x/F_y\)

Answer 2

Oh silly me, I completely forgot about that! Thank you!