You should use the fact that <i,j> = <i,k> = <j,k> = 0 and expand out the representation of E in terms of its components <a,b,c> = ai + bj + ck. where a,b,c are real valued variables.
I need some help with divergence
When I work with numbers, all is good but now I'm confused. Is the answer related to the fact that the i component only contains z and the k only contains x? So that these will become 0?
Thanks for any help.