Hi Professor Ivrii. I have a question on the attachment above. In part b, after dragging out the factor, why the remainder is (partial u)/(partial v) instead of u? Thanks.

Try again

or rather $\nabla G \cdot \frac{\partial}{\partial x}(\vec{v})$?

Hi Professor (and fellow classmates),I am wondering the same question as Thomas; specifically, does it mean this? (See attached)

I see, thanks. Are we considering closed domains, i.e. $\Sigma \in \Omega$? I think we have to, otherwise the $max_{\Omega}u \geq max_{\Sigma}u$ does not pull, correct?