Negative Times a NegativeDate: 01/12/97 at 17:31:21 From: Sue Whittaker Subject: Negative times a negative I am a student teacher who is having a hard time explaining why a negative times a negative is positive. Can you give an example? Thanks, Sue Whittaker Date: 01/12/97 at 21:39:35 From: Doctor Robert Subject: Re: Negative times a negative You can, of course, prove that a negative times a negative is a positive using the field axioms. But the best way to give a plausibility argument is to look at multiplication patterns. 3 x -3 = -9 2 x -3 = -6 1 x -3 = -3 0 x -3 = 0 -1 x -3 = 3 Voila! -Doctor Robert, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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