Re: 2 pi i = 0

[Larry Smith <larry.smith@SNOW.EDU>]

At 7:01 PM -0500 11/22/02, Michael Edmiston wrote:
> Larry Smith brings up another math thing that has changed in my
> lifetime.  When I went to school, sqrt(25) was plus-or-minus five.
> Larry says it is now just plus five.  My daughter concurs with Larry.
> Like I said, I'm getting too old.
>
> By the way.  Why is this?  Is it a calculator thing?  Sometimes I think
> math definitions are driven by what calculators do.  I remember doing
> sqrt on a slide rule (and also with pencil and paper using
> newton-raphson) and my HS math teacher would take off a point if we
> didn't put the +- sign in front of "the answer."

It depends on the way the question is asked.  There are still two square
roots of 25, +5 and -5 (fundamental thm of alg is still true), but the
radical symbol (\sqrt{25}) only denotes the positive one.  At least so the
modern algebra books say.  I don't know whether it has anything to do with
the advent of electronic calculators.

Larry

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.