(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Two point charges are placed on the x-axis as follows: one positive charge, q_{1}, is located to the right of the origin at x= x_{1}, and a second positive charge, q_{2}, is located to the left of the origin at x= x_{2}.

What is the total force (magnitude and direction) exerted by these two charges on a negative point charge, q_{3}, that is placed at the origin? Use [tex]\epsilon_{0}[/tex] for the permittivity of free space. Take positive forces to be along the positive x-axis. Do not use unit vectors.

2. Relevant equations

Coulomb's Law: F = [tex]\frac{1}{4\pi\epsilon_{0}}\frac{\left|q_{1}q_{2}\right|}{r^{2}}[/tex]

3. The attempt at a solution

http://img5.imageshack.us/img5/3753/equationu.jpg [Broken]

MasteringPhysics keeps giving me a "Check your signs error". Yet, as far as I can tell, I should be subtracting the force which is going left / the negative direction (ie, q_{2}) from the force going to the right (ie, q_{1}).

Any hints?

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# Homework Help: Force exerted by two charges

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