If M is a constant vector and r is the position vector (x;) in a right-handed system of rectangular Cartesian coordinates Ox; (i = 1,2,3) and r = [r], prove that (i) (ii) (iii) (iv) (v) curl (M^r) = 2M; div(M^r) = 0; grad M.r M p3 73 div grad r" = n(n + 1)n-2; r curl = 0. - 3 75 (M.r)r;