## About

An imaginary number **i** is one solution to <math>x^2 = -1</math>
and is a part of the definition of a complex number

<MATH> i = \sqrt { -1 } </MATH>

It was invented because formulas sometimes required the manipulation of square roots of negative numbers.

Numbers such as i, -i, 3i, 2.17i are called imaginary number.

## Articles Related

## Example

- Problem: <math>x^2 = -9</math>
- Solution: x = 3i