Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

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


Math Forum » Discussions » Education » math-teach

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

Replies: 1   Last Post: Dec 3, 2012 9:44 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Paul A. Tanner III

Posts: 5,920
Registered: 12/6/04
Re: In "square root of -1", should we say "minus 1" or "negative 1"?
Posted: Dec 3, 2012 7:43 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On Mon, Dec 3, 2012 at 6:22 PM, Joe Niederberger <niederberger@comcast.net> wrote:
> "Minus times minus makes a plus" makes perfect sense.
> In fact it emphasizes the fact the rule is based on the signs alone. The fact that negative numbers also have a magnitude is of no account whatsoever in regards to this sign rule. Think of the implied subjects and objects here being the signs, not the numbers. Or, don't, I don't care.
>


One of the standard proofs in abstract algebra textbooks of the theorem (-a)(-b) = ab for all ring elements a,b (including for rings that are not ordered) contains the equality (-a)(-b) = -(-(ab)).

Is this what you meant?

Regardless, there are ways to prove this theorem that does not use the prior theorem of additive groups x = -(-x).

And so to say that that the theorem itself (and not merely such a particular proof of it) is based on such is not right.



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.