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/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.