Three Less Than a Number
Date: 08/19/2001 at 20:34:23 From: brian clarke Subject: Algebra expressions Why is this expression driving me crazy when at first it seems so simple? three less than a number I believe it is x-3 but I am being challenged that it is 3-x.
Date: 08/20/2001 at 08:36:58 From: Doctor Peterson Subject: Re: Algebra expressions Hi, Brian. You're right: you start with the number x and decrease it by 3, so that the new number is 3 less than what you started with. Many people get confused by this sort of expression, because they expect to translate directly from English to Mathish, word for word. Then "three (3) less than (-) a number (x)" would seem to be "3-x". But it isn't. What's even more confusing is that "3 less a number" _does_ mean "3-x" because "less" as a preposition means the same as "minus." If they had enough experience translating languages, they would understand that you have to translate idea for idea. I recommend first picturing what is happening (translating English to an idea, that of decreasing a number) and then putting that into an expression. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/
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