第4个回答 2010-08-18
E means Equilibrium, at the intersection of SMC SAC and D the equilibrium represents the "break-even point" . Break-even point means the cost equals the revenue, but we must remember one thing, that is we have considered the cost of enterprenuerial ability. Therefore, the cost of enterpreneurial ability is a part of invisable profit for the industry.
The profit you said is just the money you can see, but in economists' view, the enterpreneurial ability should be involved.
Thank you and my computer cannot type Chinese, I hope the English is OK for you.