1. The problem statement, all variables and given/known data div(øu) = ødivu + ugradø 2. Relevant equations divergence of scalar field = f,ii divergence of vector field = ui,i 3. The attempt at a solution I've heard this is a simple proof, but this is my first one of 8 or so proofs I need to complete for homework, and I'm really not sure where to start. I know that div v = ∇ . v, but that's as far as I've gotten. We need to use Index Notation. Thoughts on where to start?