See attached file.© BrainMass Inc. brainmass.com December 19, 2018, 9:15 pm ad1c9bdddf
Substitute P = 1/3 u and E = u V in:
dE = T dS - P dV
to write it as:
dS = 1/T d(uV) + u/(3T) dV
d(uV) = V du + u dV to write it as:
dS = ...
A detailed derivation is given.