1. Meaning of \"Extensive\" (20 pts): Consider the Helmholz Free energy $F(N, V, T)$. The fact that $F$ is extensive can be expressed mathematically as,
$F(\lambda N, \lambda V, T) = \lambda F(N, V, T)$ (1)
From this show that
$G = F + PV = N \frac{\partial F}{\partial N}_{V, T} = \mu N$ (2)
Hint: Take derivative with respect to $\lambda$ on both sides of equation (1).