The demand curve is elastic when _______ and it is inelastic when __________.

🔑Key Points:
The demand curve is a concept in economics that plots the price of a product or service against how much of the product or service people buy.
Typically, the lower the price of an item, the more people buy.
However, that relationship varies depending on the item.
An elastic demand curve means that a change in price has a large effect on buying, while an inelastic demand curve means that a price change has less effect on buying.

🔴Additional Information:
Marginal revenue is related to the price elasticity of demand — the responsiveness of quantity demanded to a change in price.
When marginal revenue is positive, demand is elastic; and when marginal revenue is negative, demand is inelastic.
On a graph with both a demand curve and a marginal revenue curve, demand will be elastic at all quantities where marginal revenue is positive.
Demand is unit elastic at the quantity where marginal revenue is zero.                 
If the elasticity of demand is less than zero then it denotes that the change in quantity demand is opposite to the change in its own price.
It means that the slope of the demand curve is negative at this point and the marginal revenue is also negative due to negative slope.