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 Discussion: All Topics Topic: Expressions vs Equations Related Item: http://mathforum.org/mathtools/tool/99226/

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 Subject: RE: Expressions vs Equations Author: The Math Guy Date: Jan 26 2011
No, I would not consider any of those as equations.  Even in the case where you
were evaluating (replacing x, y, & z with numbers) the expression, you don't
have an equation.  If you looked at 3x+5 = 7...that is an equation.  But for
3x+5, if x = 2, then your are evaluating the expression 3x+5 when x = 2 and your
evaluation might go something like this:
3x + 5:
3(2) + 5 =
6 + 5 =
11
The "=" sign is used to separate the different forms of the expression...

But the = sign is not what is making this evaluation process into an
equation.

On the other hand,if you did write
3(2) + 5 = 11, then that equation is an Identity...true for all times just
as
cos^2 X + sin^2 X = 1  for all values of X...an identity.

Art M.