Lesson Page

 

The Imaginary Unit
 Math B

The Imaginary Unit is defined as

i = .

The reason for the name "imaginary" numbers is that when these numbers were first proposed several hundred years ago, people could not "imagine" such a number. 

 It is said that the term "imaginary" was coined by René Descartes in the seventeenth century and was meant to be a derogatory reference since, obviously, such numbers did not exist.   Today, we find the imaginary unit being used in mathematics and science.  Electrical engineers use the imaginary unit (which they represent as j ) in the study of electricity.

Imaginary numbers occur when a quadratic equation has
no roots in the set of real numbers.

 

 

 

*        i =    or   - i =  -

 

An imaginary number is a number whose square is negative.
 

 

How to use the
 TI-83+ graphing calculator
 with imaginary numbers.
Click calculator.

A pure imaginary number can be written in bi form where

b  is a real number and   i   is  .

Examples:
    pure imaginary
        numbers

 


DeMarr