4.22 Given the electric flux density \mathbf{D}=\hat{\mathbf{x}} 2(x+y)+\hat{\mathbf{y}}(3 x-2 y) \quad\left(\mathrm{C} / \mathrm{m}^{2}\right) determine (a) pv by applying Eq. (4.26), (b) the total charge Q enclosed in a cube 2

m on a side,located in the first octant with three of its sides coincident with the x, y, and z axes and one of its corners at the origin,and (c) the total charge Q in the cube, obtained by applying Eq. (4.29).