Nina: From Competition to Monopoly to Duopoly: Why MR Changes and Cartels Collapse

Описание: In this lesson, we walk through one single diagram that explains almost all of imperfect competition.
Starting from perfect competition, we explain why firms set P = MC and why marginal revenue equals price when firms are price takers.
We then move to monopoly, showing precisely why marginal revenue lies below demand, why monopolists must lower price to sell more output, and how this leads to P greater than MC and deadweight loss.
The core of the video focuses on oligopoly and cartels. Using the same demand and cost curves, we show:
• how a cartel behaves like a monopoly,
• why joint profit maximization leads to restricted output,
• and, crucially, why every firm has an incentive to cheat.
We analyze the cheater’s marginal revenue, identify the cheating output, and explain every profit area in the diagram — including cartel profits, cheating gains, and the collapse toward the competitive outcome.
This video is ideal for:
• Microeconomics students (intermediate level)
• Exam preparation (oligopoly, monopoly, game theory)
• Anyone who wants to actually understand MR, P, MC, and cartel instability instead of memorizing formulas
📌 Topics covered:
• Perfect competition vs monopoly vs duopoly
• Marginal revenue vs demand
• P = MC vs MR = MC
• Deadweight loss
• Cartels and cheating incentives
• Cournot intuition (graphical)
If you can understand this diagram, you understand oligopoly.