Separation Vector
Let \vec{r} be the separation vector from a fixed point (\acute{x},\acute{y},\acute{z}) to the source point (x,y,z).
Show that:
\nabla(\frac{1}{||\vec{r}||}) = \frac {-\hat{r}} {||\vec{r}||^2}
Now, I've attempted this comeing from the approach that ||\vec{r}|| =...