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Topic:  Is "variable" confusing to students? 
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Subject:  RE: Is 'variable' confusing to students? 
Author:  The Math Guy 
Date:  May 8 2009 
And when it is not, then the statement is false. But it can take on many
values. We don't often enough talk about the truth/falseness of the statement
and only at the case when it is true.
On May 8 2009, Susan wrote:
> I'm trying to establish the differences among the following three
> things:
3x + 5
11 = 3x + 5
y = 3x + 5
The first is an
> algebraic expression containing the "variable" x. In this case, the
> variable x can take on any value. It “varies”.
The second is an
> equation of one variable. We call x a variable but truly it doesn't
> vary. It is just an "unknown". We can solve for x and determine it
> must equal 2.
In the final case, we have two variables and they
> do 'vary' depending on each other’s values.
Should we call the x
> in the second case an “unknown” and not a variable? I’ve seen
> books say, “solve for the unknown”.
I think we confuse students
> by calling x “variables” in all of these cases when in case 2, the x
> does not vary at all.
 
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