(Solved):
The free energy is defined as follows: F=NkTln[NaV(k,T)t2] temperature of the gas, kis ...

The free energy is defined as follows: $F=NkTln[NaV(k,T)_{t}?]$ temperature of the gas, $k_{is}$ is the Boltzmann constant, and $a_{i}$ is the constant. What is the internal energy of the gas?