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 » sci.math.* » sci.math

Topic: 2 simple? questions and proposed answers
Replies: 4   Last Post: Jan 29, 2012 7:50 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Ed Wall

Posts: 837
Registered: 12/3/04
Re: 2 simple? questions and proposed answers
Posted: Jan 6, 2012 3:47 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

In a sense the business about 1 being a prime is a matter of convention (yes, it does make it easier to state some theorems). So, I would say people who are unaware of the messiness it would cause are probably right to be unimpressed.

As to multiplication of signed integers, I think saying the distribute rule has problems if not is, in fact, somewhat unconvincing (although, in a sense, what I say below is connected). Something a bit more convincing I've found (assuming people are comfortable with (a)(-b) = -(ab) [And this can be handled in a similar fashion] is simply something like

3 x -3 = -9
2 x -3 = -6
1 x -3 = -3
0 x -3 = 0
-1 x -3 = ?

Of course, mathematically the reason is that the integers are an extension of the counting numbers and hence your comment about the distributive law. The above just makes the structure a little more obvious.



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.