(A) Let be the scalar-valued function of three variables r = sqrt(x^2 + y^2 + z^2). Find grad r. (B) Find the domain of grad r. (C) Evaluate ||grad r||. (D) Remember for point P = (x, y, z), the position vector is r = <x, y, z>. Denote e_r = r/||r||. Graph the vector field e_r on its domain. (Draw two vectors in each octant.) (E) Find a scalar potential function for e_r? (Hint: You know this from previous parts.) (F) Find curl(e_r). (G) Find div(e_r).