Consider a two-date economy and a consumer with a utility function over consumption at each period u(c) = c^(1-γ)/(1-γ), where γ > 0. Define the intertemporal utility function as v(c1, c2) = u(c1) + u(c2). Show that the consumer will always prefer a smooth consumption stream to a more variable one with the same mean, i.e., v((c1 + c2)/2, (c1 + c2)/2) > v(c1, c2).