Demand function is an important tool used in economics to understand the relationship between the quantity of a product demanded and the factors affecting it. A demand function is a mathematical equation that shows how the quantity of a product demanded varies with changes in its price, income, tastes, preferences, and other factors.

Relationship between Quantity Demanded and Factors Affecting it
The demand function shows the relationship between the quantity demanded of a product and the factors affecting it. These factors can include the price of the product, income of the consumers, availability of substitutes, tastes and preferences of the consumers, and other economic and non-economic factors. By analyzing the demand function, economists can understand the impact of each of these factors on the quantity demanded of the product.

Mathematical Representation
A demand function is usually represented in the form of an equation, such as Qd = f(P, Y, Ps, T, E), where Qd is the quantity demanded of the product, P is the price of the product, Y is the income of the consumers, Ps is the price of substitutes, T is the tastes and preferences of the consumers, and E is other economic and non-economic factors affecting the demand.

Impact of Price and Income
The demand function shows the relationship between the quantity demanded and the price of the product. The law of demand states that as the price of a product increases, the quantity demanded of the product decreases, and vice versa. Similarly, the relationship between the quantity demanded and income of the consumers is also shown by the demand function. As the income of the consumers increases, the demand for normal goods increases, while the demand for inferior goods decreases.

Conclusion
In conclusion, a demand function is an important tool used in economics to understand the relationship between the quantity demanded of a product and the factors affecting it. It is represented in the form of a mathematical equation and helps economists understand the impact of price, income, tastes, preferences, and other factors on the demand for a product.

The constant "b" is the slope of the demand curve and shows how the price of the good affects the quantity demanded. The graph of the demand curve uses the inverse demand function in which price is expressed as a function of quantity. ... These "other variables" are part of the demand function.