Chapter 1
Linear Equations and Graphing
Course: Gre
Subject: Gre Quantitative Reasoning
Chapter: Quadratic Equations And Polynomials
Introduction: What Is a Function?
In everyday language, the word "function" appears frequently. A vending machine functions by dispensing a drink when a button is pressed. A calculator functions by producing an answer when numbers are entered. In mathematics, the concept is similar: a function is a rule that takes an input and produces exactly one output.
Functions are everywhere. The grade you receive on a test is a function of your score. The cost of groceries is a function of what you buy. The monthly cable bill is a function of the channels you select. Understanding functions provides a framework for describing relationships between quantities.
Identifying Functions
A function is a special type of relationship between inputs and outputs. The defining characteristic is consistency: each input must correspond to exactly one output.