Complex Numbers

The simplest way to define a complex or imaginary number is a number that is a multiple of i in which i is defined by the property of i squared equals -1.
This is puzzling to most people, because it is hard to imagine any number having a negative square. The result: it is tempting to believe that i doesn't really exist, but is just a convenient mathematical fiction.
This isn't the case. Imaginary numbers do exist. Despite their name, they are not really imaginary at all. (The name dates back to when they were first introduced, before their existence was really understood. …