(a) Let $\mbox{div }\vec F=x^2+y^2+z^2+2$. Calculate $\int_{S_1}\vec F\cdot d\vec A$ where $S_1$ is the sphere of radius 1 centered at the origin.
$\int_{S_1}\vec F\cdot d\vec A =$

(b) Let $S_2$ be the sphere of radius 3 centered at the origin; let $S_3$ be the sphere of radius 4 centered at the origin; let $S_4$ be the box of side 8 centered at the origin with edges parallel to the axes. Without calculating them, arrange the following integrals in increasing order: $$A = \int_{S_2}\vec F\cdot d\vec A,\quad B = \int_{S_3}\vec F\cdot d\vec A, \quad C = \int_{S_4}\vec F\cdot d\vec A.$$