In this video I will explain long run supply curve of the industry under perfect competition. we know the long-run supply curve of a perfectly competitive industry indicates various quantities of a product being offered in the market at various prices. In this lecture i will explain last shape of industry Supply Curve: Supply Curve Of Decreasing Cost Industry:- An Industry is said to be decreasing cost industry when the prices of factors of Production fall as the industry expands. when new firms enter in the long run due to increased demand, additional supply will be produced at lower price then cost would be reduced with the expansion of the industry. The cost curves will shift downward. So the long- run supply curve (LRS) has negative slope.