In Exercises $1-3,$ begin by drawing a diagram that shows the relations among the variables.
Let $U=f(P, V, T)$ be the internal energy of a gas that obeys the ideal gas law $P V=n R T(n$ and $R$ constant). Find a. $\left(\frac{\partial U}{\partial P}\right)_{V} \quad$ b. $\left(\frac{\partial U}{\partial T}\right)_{V}$