trying to find the electric field on a point charge. I have the answer, just need to know the process?

Question

Here is the question in detail: Three charges form an equilateral triangle of side a. At one vertex is a charge +2q; at the other two vertices are charges -q. The triangle is oriented with the charge 2q on the positive x axis and both charges -q on the y axis. a) Find an expression for the electric field on the x axis, in the approximation x>>a. b) give an expression for the magnitude of the triangle's dipole moment. Answers: a) E=2(3)^½kqa/x^3 i, E and i are vectors b) p=(3)^½qa

Answer 1

Find my analysis here:

Page 1 http://img182.imageshack.us/img182/1619/electfieldp1rf0.png
Page 2 http://img182.imageshack.us/img182/5769/electfield3p2hi2.png