## calc 3: need help computing div E

NOTE: r and k are vectors

The electric field E of a dipole with moment k located at the origin is given by

E(r) = (3zr/||r||⁵) − (k/||r||³)

a) Compute div E.

I understand ||r|| = √x² + y ² + z² but the k is confusing me..please help..