Well, it IS a "partial differential equation". Have you learned how to solve such things? The "[math]\nabla[/math]" on the right is the differential operator [math]\frac{\partial}{\partial x}+ \frac{\partial}{\partial y}+ \frac{\partial}{\partial z}[/math]. I have a little problem with the left side. It is not clear to me whether that "P( )" means that P is a function of the quantity in the parentheses or whether it just means P times that quantity. Also there is a "g" on the right but not on the left. Is there another part of the problem that defines g?
