[domingo2000]

Hi, my question is the following, if I need to find the parameters of an equation of state in function of the Critical Conditions, hoy many times can I calculate the partial derivative and make it equal to 0, for example, to find the a and b of the van der waals equation of state, with the first and second derivative equal to 0 you can find the parameters inf function of the critical conditions (Pc,Tc and Vc).
In a homework i have an equation of state of grade 4 and i dont know if a can calculate the third derivative and make it equal to 0