The figure can be drawn according to given conditions.
Where, in the above figure at the point the charge is , at the point the charge is and at the point the charge is .
The distances are given as,
The electrostatic potential at point is given as,
By substituting the given values in the above expression, we get
Since, the value of , So and the term can be neglected.
The value of electric potential is given as,
Thus, the expression of electrical potential is , for a dipole is and for a monopole system is .