The document discusses the concept of demand in mathematical terms. It states that the amount consumers demand of a product (Qx) is a function of the price of the product (Px), the price of other goods (Py), consumer tastes and preferences (T), consumer income (M), and the number of consumers (N). It provides examples of linear and nonlinear demand curves expressed as mathematical equations, and explains how to calculate the total market demand by adding individual demand curves.