Electric field of point charges

[dh743]

Homework Statement

A 4microC point charge is placed at the coordinate origin. Two other point charges are placed on the x axis: q1 at x=30cm and q2 at x=50cm. Find the magnitude and sign of q1 and q2 if the net force on each of the three charges is zero.

Homework Equations

E=$$\frac{kq}{r²}$$

The Attempt at a Solution

I tried using F=$$\frac{kqQ}{r²}$$ to find the relationship between the points (i.e. let one equal the other) but I'm basically just completely stumped on this one so any help is greatly appreciated.

 

[tiny-tim]

hi dh743!

(try using the X² and X₂ icons just above the Reply box )

show us your full calculations, and then we'll see what went wrong, and we'll know how to help