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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: Hemiboso Date: Jan 26 2011
Thank you very much taking the time to answer my (probably naive) question (I'm
obviously a non-mathematician). I'm still mulling over your response, but I
think I get it :-).

On Jan 26 2011, The Math Guy wrote:
> 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.
==================================================
Posted:  Jan 26 2011
By:
Subject: RE: Expressions vs Equations

Would you consider x^n * y^n ± z^n (where x=2, y=3 and z=5) an equation, formula
or expression?

Note the absence of an equal sign.

However, when you populate the "formula" (if that's what it is) it decidedly
becomes an equality viz. equation, e.g., 2^3 * 3^2 - 5 = 67

(all integers in the set of natural numbers not divisible by 2, 3 and 5 can be
generated with this "formula") (ref: www.primesdemystified.com )

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