Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Topic: Re: In "square root of -1", should we say "minus 1" or "negative
1"?

Replies: 1   Last Post: Dec 4, 2012 11:07 AM

 Messages: [ Previous | Next ]
 Robert Hansen Posts: 11,253 From: Florida Registered: 6/22/09
Re: In "square root of -1", should we say "minus 1" or "negative 1"?
Posted: Dec 4, 2012 11:07 AM

On Dec 4, 2012, at 10:40 AM, Joe Niederberger <niederberger@comcast.net> wrote:

> R. Hansen says:
> - -----------------------------------------
> I was thinking...
> (3) * (-2) = (-2) + (-2) + (-2) = -2 - 2 - 2
> Or the other way around ...
> (-2) * (3) = - 3 - 3 (repeated subtraction) (I just realized so much for crabtree's subtracted once from itself theory, that was an unexpected bonus)
> And with two negatives...
> (-2) * (-3) = - (-3) - (-3) (thus, when you are subtracting a minus you are actually adding)
> - ----------------------------------------------
>
> That's kind of cute -- I like it.
> But I think to make it solid you would have to
> define multiplication of (+)x(-) and (-)x(+)
> first, and treat them asymmetrically!
>
> Cheers,
> Joe N

I was thinking subtracting twice, not the product of signs. Like, "What is zero minus a minus 3?"

Bob Hansen

Date Subject Author
12/4/12 Joe Niederberger
12/4/12 Robert Hansen