In a certain two-dimensional field of force the potential energy of a particle has the form U = ax2 + y2, where a and are

In a certain two-dimensional field of force the potential energy of a particle has the form U = ax2 + βy2, where a and β are positive constants whose magnitudes are different. Find out:
(a) Whether this field is central;
(b) What is the shape of the equipotential surfaces and also of the surfaces for which the magnitude of the vector of force F = const