1. The problem statement, all variables and given/known data A slab of insulating material has thickness 2d and is oriented so that its faces are parallel to the yz-plane and given by the planes x = d and x = -d. The y- and z- dimensions of the slab are very large compared to d and may be treated as essentially infinite. 2. Relevant equations The charge density of the slab is given by ρ(x) = ρ0 * (x/d)^2 , where ρ0 is a positive constant. Using Gauss Law, find the electric field due to the slab (magnitude and direction) at all points in space. 3. The attempt at a solution Attached is a picture of my attempted solution. I don't know why both my answers are off by a factor of 2, could somebody explain? The answer given is: |x| > d: (ρ0d)/(3ε) ; |x| < d: (ρ0x^3)/(3εd^2). Thanks!