can you solve exercise 71 in detail step by step so I can compare my own work

Variations There are also variations of Gauss' theorem. Exercise 71 Show that, if o is a scalar field, Exercise 72 Show that, if V is a vector field, IN THE $ ( x vids = /// (v xviav. (96) Exercise 73 By applying Gauss' theorem to the vector V = V6, where y and d are both functions with well-defined derivatives on S and throughout V, prove that 1/1 (vv?$ + Vy. vo)dy= #/ vVonds. (97)