The figure represents a combination of charges called an electric quadrupole, where q > 0. Find the resulting electric field existing (a) at point A (x, 0); (b) at point B(0, y). (c) Show that, for point A or point B, E ? 1/r^4 for r >> a, where r is the distance from the origin. (Hint: Use the binomial approximation (1 + z)^n ? 1 + nz, valid when z

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