Ah yes! It appears I did. However, even without having it I was getting 126 J. It says that the answer is -105 J. So that tells me I messed up somewhere while calculating with all the ##U_e##'s.
I don't have access to my work atm as I am not home. I will make sure to post it as soon I get the...
Homework Statement
An object with charge +2.0×10−5 C is moved from position C to position D in the figure (Figure 1) . q1 = q3 = +10.0×10−5 C and q2 = −20.0×10−5 C. All four charged objects are the system.
Here's a picture to the problem
Homework Equations
$$ F = \frac {kq_1 q_2}{r^2} $$
$$...