Definition Of Imaginary Number

An Imaginary Number is a number in the form of ai, where a is any real number and i² = - 1 or  .

More About Imaginary Number

Imaginary numbers are represented on the vertical axis on a complex number plane.
Zero (0) is the only number that is considered both real and imaginary.

Video Examples: Introduction to i and Imaginary Numbers
 

Example of Imaginary Number

2i is an imaginary number.

Solved Example on Imaginary Number

Ques: Identify the imaginary number from the following.

Choices:

A. 22 
B. √-4
C. √2
D. -11/125
Correct Answer: B

Solution:

Step 1: A number of the form ai, where a is any real number and i² = - 1 or is called an Imaginary Number.
Step 2: Here, √-4 is an imaginary number. [√-4 = 2i]

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