PRACTICE EXERCISE 4.8 If D= (2y²+ z)a, + 4xya, + xa, C/m², find (a) The volume charge density at (-1, 0, 3) (b) The flux through the cube defined by 0 ≤x≤ 1,0 sy≤ 1,0 ≤ z ≤ 1 (c) The total charge enclosed by the cube Answer: (a)-4 C/m³, (b) 2 C, (c) 2 C.