Where on the x-axis is the potential zero

[jenzao]

Homework Statement

Is this question on electric potential solvable? I've tried everything. any ideas?
A charge of -1.9 × 10-9 C is at the origin and a charge of 9.4 × 10-9 C is on the x-axis at x = 3 m. At what two locations on the x-axis (xpositive, xnegative) is the potential zero?

Homework Equations

The Attempt at a Solution

heres what i did...

kq1/r1 = kq2/r2

first i canceled k because its on both sides, and a constant..
then i solved for r1...

r1 = r2q1/q2

then i added the values...

r1 = 3(-1.9e-9) / (9.4e-9)

answer = .606

this is wrong... please help! thanks

 

[nealh149]

Think about what your variables r1 and r2 mean here.

 

[jenzao]

r is the distance from the charge where the potential is zero isn't it?