Three charges 2q, -q, -q are located at the vertices of an,equilateral triangle. At the centre of the triangle

Obviously, from charge configuration, at the centre electric field is non-zero. Potential at the centre due to 2q charge V2q=2kqrand potential due to - q chargeV-q=-kqr (r = distance of centre point)∴ Total potential V=V2q+V-q+V-q=0