5. Consider an isosceles triangle of charges. At (a, 0), there is a 7 nC charge. At(-a, 0), there is a 5 nC charge. At (0, b), there is a 2 nC charge. Here a = 5 m and b = 4.6 m. Calculate the electric potential at the origin, in V. Use k = 9 x 109N m2 / C2.

Fig: 1