The following is a sketch of the amount of a particular brand of coffee sold by a store as a function of the price of the coffee:
Work Step by Step
The amount of coffee sold is represented in the y-axis of the graph, whereas the price of the coffee is represented in the x-axis. At a low price (ie. x-value), the amount of coffee sold is high (y-value). As the price increases, the amount of coffee sold decreases. The amount of coffee sold tends to zero as the price increases. The x-value is always positive since there cannot be a negative price. The y-value is always either positive or zero since there cannot be a negative amount sold.