Topic : coulomb’s law

Two identical charged conducting spheres A and B have their centres separated by a certain distance. Charge on each sphere is q and the force of repulsion between them is F. A third identical uncharged conducting sphere is brought in contact with sphere A first and then with B and finally removed from both. New force of repulsion between spheres A and B (Radii of A and B are negligible compared to the distance of separation so that for calculating force between them they can be considered as point charges) is best given as:

A point charge of 1 μC is placed at a point A(1, 0, 0) m and another identical charge is placed at B(0, 0, 1) m. The force between them is