Walker, Halliday & Resnick — Gauss' Law: Problem 36

36 In Fig. 23-40, short sections of two very long parallel lines of charge are shown, fixed in place, separated by $L = 10.0\text{ cm}$. The uniform linear charge densities are $+6.0\text{ }\mu\text{C/m}$ for line 1 and $-2.0\text{ }\mu\text{C/m}$ for line 2. Where along the x axis shown is the net electric field from the two lines zero?