Suppose a firm has the following production function: Q=12KL+KL^2-(1/12)KL^3 If the firm is operating in the short run and capital (K) is fixed at K = 4, determine the following: The maximum output that the firm can produce when K = 4. The level of input L where APL is at a maximum. The output level where diminishing marginal returns to input L occurs. The level of input L where MPL is zero.