## Principles of Microeconomics, 7th Edition

Since we know that the demand for the good is elastic, this means that an increase in price will cause a decrease in quantity demanded that is greater in magnitude than the change in price. The formula to calculate total revenue is $Q \times P$, and since we know that an increase in P will cause a decrease in Q of greater magnitude, we know that total revenue must decrease mathematically as a result of the price increase.