Three charges, $+5$Q$,-5$Q$,$ and $+3$Q are located on the y$-$axis at y $=+4$a$,$ y$=0,$ and y$=4$a$,$

respectively. The point P is on the x$-$axis at x $=3$a$.$

a$)$ How much energy did it take to assemble these charges?

b$)$ What are the x$,$ y$,$ and z components of the electric field E at P$?$

c$)$ What is the electric potential $$ at point P$,$ taking $=0$ at infinity?

d$)$ A fourth charge of $+$Q is brought to P from infinity. What are the x$,$ y$,$ and z components of

the force F that is exerted on it by the other three charges?