eco. (derived demand and complement 有咩分別)

derived demand (衍生需求) is the demand for factors of production (生產的因素).

factors of production :
1. labour ( you employ labour to produce goods for you)
2. materials used in making production


EXAMPLE:
take the demand for cement (水泥) an example. People have demand for cement because they need cement(a kind of raw materials ) to build house. The demand for cement is derived from the demand for housing, but the cement itself. So, cement is a derived demand.


complement demand (補給品需求) :
good A and good B are said to be complement if they are necessary to be used together.

EXAMPLE:
DVD & DVD player
if the price of DVD player increases, its quantity demanded decreases so that the demand for DVD is relatively decreases.