First I have a simple question for you: Are you incapable of using proper English constructions? Why do you make yourself look foolish by using "chat-speak" when discussing a serious topic.

Second, there is no such thing as "

underroot(-1)" If you are serious then learn to use symbols. [TEX]\sqrt{-1}[/TEX] gives

. You are not too lazy to take the time to type that are you?

Now to your question. If I were living pre-sixteenth century and saw "

", I would say "what fool wrote that?'

But from the year 1609 on, the idea of complex numbers has become well understood. It has been developed into a consistent theory.

Do you even understand that "iota",

is a Greek letter not to be confused with the mathematical symbol

, which is used to stand for the principal root of

And that is you answer as to what is is used for: it completes the number system giving us the

fundamental theorem of algebra.