Three electrons form an equilateral triangle

[t.kirschner99]

1. Homework Statement

Three electrons form an equilateral triangle 1.00nm on each side. A proton is at the center of the triangle. What is the potential energy of this group of charges?
Known Variables:
s = 1.00 × 10^-9m
p⁺ Charge = 1.60 × 10^-19C
e^- Charge = -1.60 × 10^-19C
r = s/√(3) = 5.77 × 10^-10m

Homework Equations

ΔU = (kq₁q₂)/ r

The Attempt at a Solution

[/B]
ΔU = k[(3(-1.60×10^-19)²))/(1.00×10^-9) - ((3(1.60×10^-19)(-1.60×^-19))/(5.77 × 10^-10))]

For some reason I cannot get the answer, and I was wondering if anyone could spot my error. Thanks!

 

[Delta2]

The term with denominator 5.77x10^-10 should be negative but you have a double minus sign which makes it positive. The potential energy of the proton due to the 3 electrons should be negative due to the attraction.