How do you get functional equation of demand?

To derive the functional equation of demand, start with the basic principles of consumer choice, which involve preferences, budget constraints, and utility maximization. Typically, the demand function can be expressed as a function of price, income, and preferences. By applying methods like the utility maximization problem and incorporating factors such as price elasticity, you can derive a mathematical representation of the demand for goods. Finally, empirical data can be used to estimate the parameters of the demand function, ensuring it reflects real-world consumer behavior.