Hey everyone, I'm not sure if this belongs in the math or physics section of this forum, but I figure since my question is more related to the mathematical manipulation of what I am dealing with, I figured I would ask it here and then if it has to be moved, it can be. My question has to do with applying gauss' law to a differential equation I am dealing with. The differential equation is the partial derivative of some function of x,y,z,t with respect to t is equal to a constant times dell^2 of that function plus another constant times the same function. The case I am considering is when the time derivative is equal to zero. So I have: D*dell^2(n) + C*n = 0 So I am thinking I am basically dealing with a divergence of the vector dell(n) (n is a scalar function). However, I'm not sure how to apply that logic to the C*n part. Can I just subtract it to the other side and take the triple volume integral? Or does the divergence theorem not apply? I think it does because I am basically dealing with a diffusion of particles out from a spherical surface. The only difference is there are particles being generated inside of the sphere as well. That's the C*n term.