A particle that carries charge \(+4 q\) is located at the origin of an \(x\) axis, and a uniformly charged nonconducting solid sphere of radius \(R\) and carrying charge \(+q\) is centered at \(x=+6 R\) on the \(x\) axis.

(a) At what locations on the \(x\) axis is the electric field zero? 

\((b)\) If the nonconducting sphere is replaced by a conducting sphere of the same radius and carrying the same charge, would the answers to part \(a\) change?