The dependence of Thermodynamic Quantities on Volume for a non-Perfect Gas

Do not use either dA = dU - TdS or dG = dH - TdS

If the equation of state is pV^3=nRT for an isothermal process of two moles of a gas expanding from 2L to 3L at 25oC. (1Latm = 101J)

a. what is the internal energy (dU) in kJ

b. what is the Gibbs free energy (dG) in kJ

c. what is the enthalpy (dH) in kJ