Unlike an aggregate demand curve, the only factors that are allowed to vary on a market curve are the price of the product and the quantity of the product, according to Pearson Education.

The relationship between supply and demand can be expressed using an aggregate supply or aggregate demand curve. Using this economic law, businesses create better forecasts for future production ...

Increasing aggregate demand usually corresponds with increasing price levels while decreasing demand corresponds with lower price levels. But the link isn't always clear.

Using the same example, the integral of the demand curve would be 6x, minus one half times x raised to the power of 2. The definite integral from 0 to 4 would be equal to 16.