Electric Force Calculation for Particle 2

[Zythyr]

Homework Statement

http://img155.imageshack.us/img155/5661/q2gf2.jpg

The Attempt at a Solution

I got the first part of the question correct but for some reason I can't get the second one. I know I did it correctly but its not working.

All the forces acting on particle 2 are from particle 1, 3, and 4. I calculated the forces and added them up but I still am not getting the right answer. I tried both negative and positive answer for the same number and still it says I am wrong.

 

[malawi_glenn]

you have still not said anything about the results of your procedures. Then how can we tell you where you did wrong?

 

[Zythyr]

F2 = F21 + F23 + F24

F21 = Kq1q2/d^2 (convert d to meters first)
F23 = Kq2q3/d^2 (convert d to meters first)

F24 = Kq2q4/(2*d)^2 (convert d to meters first)

Also I am not sure if the final answer is suppose to be negitive or positive.