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**1. Homework Statement**

A charge q=3.87*(10 to the 9th) Coloumbs is placed at the origin and a second charge equal to -2q is placed on the x axis at the location x=1.5m. (a) Find the electric potential midway between the two charges. (b) THe electric potential vanishes at some point between the two charges. Find the value of x at this point.

**2. Homework Equations**

U=(kq0q)/r

U=(kq)/r

U= U1 + U2

**3. The Attempt at a Solution**

(a)

U=(8.99*(10 to the 9th)(3.87*10to the -9th)(-1.9*10to the -9th))/.75

+

U=(9*(10 to the 9th)(-7.74*10to the -9th)(-1.9*10to the -9th))/.75

=

8.2*10to the 10th???????

(b)

0=((8.99*10to the 9th)(???))/r