Today we can discuss a topic from functions.

Definitions:

Function
Let A anb B be two non empty sets. A function "f" from a set A to a set B is a rule so that to each element x in A there corresponds exactly one element y in B, under f ,then we say that f is a functin from A to B and write
f:A -> B

y is called the image of x under f and is denoted by f(x). x and y are respectively called the independent variable and the dependent variable. We also say that y is a function of x and write
y=f(x)

Examples:

1. 
   In the family of circles, the area A of the circle is a function of radius r of the circle.
   Here radius r is the independent variable and area A is the dependent variable
2. 
   The speed of a chemical reaction increases 2 times with the addition of every 5 milligrams of a catalyst. Here the amount of catalyst is the independent variable and speed of the chemical reaction is the dependent variable.