et's make this rigorous with two good k and l, where we look at labor demand, the price of labor is w, the price of capital is R Just plugging into the formula gives us 斧=?爷斧 is more useful to also use the two first order conditions and note that 作+B and PkK /K=0. /W Manipulating these equations yields PfulfKK? Ph oLet’s make this rigorous with two good K and L, where we look at labor demand, the price of labor is W, the price of capital is R. Just plugging into the formula gives us: W L /L /W = 1 L ? RK WL W K /K /W It is more useful to also use the two first order conditions and note that fLL /L /W + PfKL /K /W = 1 and PfKL /L /W + PfKK /K /W = 0. Manipulating these equations yields: /L /W = fKK PfLLfKK ? PfKL 2 < 0