Re: Why should -1 multiplied by -1 be plus 1 and not -1

From: >parr\(*> (gniKyruaL_at_tenretnitb.moc)
Date: 07/30/04 

Date: Fri, 30 Jul 2004 20:04:44 +0000 (UTC)

">parr(*>" <gniKyruaL@tenretnitb.moc> wrote in message
news:ced5oc$i55$3@titan.btinternet.com...
| This is a genuine question, but not mine. Some years ago, I knew a
| girl, of a certain age, who could not understand why. Nor could I
| find a logical/mathematical argument to show her. It's not that
she
| rejected the agreed arithmetical result, it's just that her
intuition
| told her that two minuses should not become positive.
|
| I didn't spend a lot of time in the process because we had mutually
| interesting things to discuss.
|
| This girl was no slouch, but did not have a mathematical aptitude.
| In fact to reassure herself that she had something above neck
level,
| she had applied to and been accepted into Mensa.
|
| So here's the problem or you logic buffs: How would you present a
| case that
| -1 x -1 = +1
| to someone whose intuition told her that it really ought to
equal -1?
|
| (If this intuition versus logic problem bears an uncanny
resemblance
| to another topic, it may be intentional:)

Cripes! 7 replies so far and I'm not even asleep yet!

Thank you all for replying. I will be slow at responding to your
replies because I >parr> have to work out the sorts of problems my
friend, I'll call her Gina, (Kurly Gina) would have.

I'm unlikely to reply to your interactions. In fact, I'm still
trying to decide whether to not read them in order that I don't
preempt things.

OK, I've just decided, I'll try not to peek. This will mean you may
get something similar to someone lse's observation.

In my replies, Gina will make 'her' response. Sometimes <parr< will
add some comment which may explain Gina's reply.

Bear with me, please, I trust it will be a more satisfying exercise
of practical logic that the show over the road. 

--
)>==ss$$%PARR(º>   Parr

Relevant Pages

  • Ginas multiplication problem - what I got out of it
    ... This is a review of what I got out of the replies to recent post I ... I've changed my mind, Peter Kook, it is. ... So my intuition whispered, 'do an experiment'. ... negation being reversing looks good. ...
    (sci.logic)
  • Re: The empty set
    ... Two of my replies to apoorv, are not displaying in a certain news ... (There's a redundancy in that definition for Z set theories, ... If that is the common non-mathematical intuition, ...
    (sci.logic)
  • Re: Why should -1 multiplied by -1 be plus 1 and not -1
    ... Had you said that to Gina, ... But I already knew that's the way to multiply minus numbers, ... I did this sort of thing at school. ... multiplication tables, I (parr) thought, this must convince Gina. ...
    (sci.logic)
  • Re: GINA free for Win2000
    ... Do a Google search for "GINA replacement". ... * PLEASE post all messages and replies in the newsgroups ... > Some enterprise pcs enables their customized Windows Logon, ...
    (microsoft.public.win2000.networking)
  • Re: Why should -1 multiplied by -1 be plus 1 and not -1
    ... > the distributive law would help fix someone's wrong intuition? ... "Intuition" is a vague term: there is a "intuition" which grows ... ONLY alternative for Gina is between -1 and 1 this would explain why ... implies C which ... ...
    (sci.logic)