Chapter 6.6, Problem 20P

As in Problem 17, find the following gradients in two ways and show that your answers are equivalent.

Find $\nabla r$, where $r=\sqrt{x^2+y^2}$, using ( 6.7) and also using $(6.3).$ Show that your results are the same by using (4.11) and (4.12).

$\nabla \left(r^2\right)$