How Long Run Marginal Cost Curve is Derived from the Short Run Marginal Cost Curves?
            The long run marginal cost (LMC) curve shows the minimum amount by which cost is inÂcreased each time, when output is increased or the maximum amount of total cost that can be reduced, when output is reduced.LMC curve is derived from the short run marginal cost (SMC) curves by considering the points of intersection of the SMCs, with vertical lines drawn from the points of tangency of corresponding SAC and LAC curve to the X-axis. This is illustrated in Fig. 9.14, where initially LAC curve is drawn through short- run average cost (SAC) curves. For the sake of simplicity, only three SAC curves have been considered.In the long run, if the firm wants to produce OQ, output, it will choose the plant correÂsponding to SAC1. For this level of output,…