We know from equation (8.2) that 7rw = –L < 0, so that the slope of an iso-profit line is determined by the sign of irL. But 71, AFL – w, and FLL < 0, so that 771 is positive for a low employment level, becomes zero (at the profit-maximizing point), and then turns negative as employment increases further. Hence, in terms of Figure 8.1, the iso-profit curves are upward sloping to the left of the labour demand schedule, downward sloping to the right of labour demand, and attain a maximum for points on the labour demand schedule. In Figure 8.1 a number of iso-profit curves have been drawn, each associated with a different level of profit. Obviously, for a given