Re: A dead subject

From: Laserman (jimzotos_at_yahoo.com)
Date: 08/04/04 

Date: 3 Aug 2004 17:52:37 -0700

"Robert J. Kolker" <robert_kolker@hotmail.com> wrote in message news:<qBrOc.58732$eM2.33243@attbi_s51>...
> Laserman wrote:
>
> >
> > Stephen, if you were learning the formula from scratch which one would
> > you prefer to learn? The more complicated one with the extra minus
> > signs that cause havoc among novices or my version?
>
> That standard formula works in the more general space of complex
> numbers. I think it was Gauss that proved than any polynomial in a
> single complex variable with real co-efficients has a complex root and
> that roots come in conjugate pairs for those with a non-zero imaginary part.
>
> As far as "ease of computation", one need only check the discrimant
> b^2 - 4ac to see if it is positive. If one does not like complex roots
> he can ignore quadratics with negative discriminant.
>
> Bob Kolker

Bob, you can look at my discriminant b^2 + 4ac for the same thing.
The important thing is that the expression underneath the radical is
positive, not how the expression is written (if you are interested in
real roots) The "standard" formula is about the clumsiest way you can
solve second degree equations.