Associated Topics || Dr. Math Home || Search Dr. Math

### Sign Switching

```
Date: 01/28/2002 at 09:16:51
From: Marielle
Subject: Multiplying / dividing inequalities

Can you explain sign switching for me? I don't get why or when the
sign switches.
```

```
Date: 01/28/2002 at 11:45:27
From: Doctor Ian
Subject: Re: Multiplying / dividing inequalities

Hi Marielle,

I think this answer from the Dr. Math archives will tell you what you
want to know, but write back if it isn't clear, or if you still have
questions.

Negatives and Inequalities
http://mathforum.org/dr.math/problems/jain9.10.98.html

For what it's worth, you might try thinking in terms of maintaining an
advantage.  For example, if I have more of something than someone
else,

my stuff > his stuff

then if each of us adds or subtracts the same amount of stuff, I'll
still be better off; and if we each multiply what we have by some
positive amount, I'll still be better off.

But what happens if we both convert our assets into the same amount of
debt?  (That is, for every dollar of assets I had, I now have a dollar
of debt.) In that case, the better off I am to begin with, the worse
off I am after the switch.

Does this help?

- Doctor Ian, The Math Forum
http://mathforum.org/dr.math/

```
Associated Topics:
High School Basic Algebra
Middle School Algebra

Search the Dr. Math Library:

 Find items containing (put spaces between keywords):   Click only once for faster results: [ Choose "whole words" when searching for a word like age.] all keywords, in any order at least one, that exact phrase parts of words whole words

Submit your own question to Dr. Math
Math Forum Home || Math Library || Quick Reference || Math Forum Search