Demand Function, Schedule & Curve
Class 11 Micro Economics — The three ways to express the price-quantity relationship
Demand Function
The demand function expresses the relationship between demand for a commodity and its determinants in mathematical form.
Individual Demand Function
Pₓ
Price of x
Pᵣ
Related goods price
Y
Income
T
Tastes
E
Expectations
Simple Demand Function
For analysis, only own price is considered keeping other factors constant: Dₓ = f(Pₓ) — there is an inverse relationship between demand and price.
Interactive: Dₓ = 100 − 2Pₓ
Demand Schedule
A demand schedule is a tabular statement showing different quantities demanded at various prices during a given period.
| Price (₹) | Quantity Demanded (units) |
|---|---|
| 5 | 1 |
| 4 | 2 |
| 3 | 3 |
| 2 | 4 |
| 1 | 5 |
Demand vs Quantity Demanded
Demand refers to the entire schedule (all price-quantity combinations). Quantity Demanded refers to a specific quantity at a specific price — it is just one point in the relationship.
Demand Curve and Slope
The demand curve is a graphical representation of the demand schedule. It slopes downward from left to right, showing the inverse relationship between price and quantity demanded.
Step 1: Plot Points from Schedule
Interactive Graph
Key Takeaways
- The demand function shows the functional relationship: Dₓ = f(Pₓ, Pᵣ, Y, T, E) — for individual demand.
- Market demand function includes additional factors: population (N), income distribution (D), and season (S).
- The demand schedule is a table showing price-quantity pairs. Demand = entire schedule; Quantity Demanded = one point.
- The demand curve (DD) slopes downward from left to right — slope is negative, confirming the inverse relationship.
- Market demand curve is the horizontal summation of all individual demand curves.