# Imaginary Number i

How to use the imaginary number i to simiplify the square root of a negative number: definition, 1 example, and its solution.

## Definition

i = √-1

The number in the square root sign

cannot be (-).

So i = √-1 is not a real number.

This is why

i is called the imaginary number.

## Example√-36

Solution

Solution (Detail)

The minus sign inside the square root means i.

So √-36 = √36i.

36 = 6^{2}

Cancel the square root and the square.

Then √6^{2}i = 6i.

So 6i is the answer.