The electric potential is defined by the function v(x,y,z) =

[Joa Boaz]

My approach and solution, but not sure if it is correct path:

 

[Orodruin]

I would suggest you give us your reasoning and middle steps rater than just providing your final answer in your proposed solution. It will make it much more obvious where you go wrong if you do. I checked the first term only, which looks reasonable apart from the exponent of the z factor. I am guessing you are on the correct track but I really cannot tell if you do not give more details.

I would also keep each term as it is and not try to put it on a common denominator, it will make it more apparent where each term comes from.