Question

the price elasticity of demand is equal to one for a demand curve wich is

Answer 1

When the price elasticity of demand for a good is relatively inelastic (-1 < Ed < 0), the percentage change in quantity demanded is smaller than that inprice. Hence, when the price is raised, the total revenue increases, and vice versa.

Answer 2

The price elasticity of demand is equal to one for a demand curve which is unitary elastic.

1. It implies that there will be a proportionate  change in the demand  with respect to change in price.
2. This doesn't mean exact change but it implies that ratio of change will be same.
3. So, when the price falls the demand will increase in the same proportion and vice versa. For e.g. a 5 % fall in price will lead to a 5% increase in demand.