Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
_____________________________________________
Associated Topics || Dr. Math Home || Search Dr. Math
_____________________________________________

Equivalent Expressions / Equivalent Equations


Date: 07/27/97 at 13:12:25
From: Anonymous
Subject: Equivalent expressions and equivalent equations

Dr. Math,

Could you please explain the difference between equivalent expressions 
and equivalent equations?

Thank you,
Linda


Date: 07/29/97 at 11:33:50
From: Doctor Rob
Subject: Re: Equivalent expressions and equivalent equations

Good question!  This is often a source of confusion to students.

Equivalent expressions have the same value for every possible value of
the variables they include.  5*(x-4) and 5*x - 20 are equivalent
expressions because no matter what the value of x, they are equal in 
value.

Equivalent equations are ones such that the truth of one implies and
is implied by the truth of the other.  (y-2)^2 = 0 and y = 2 are
equivalent equations, even though the expressions y and (y-2)^2 are
not equivalent expressions.

-Doctor Rob,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Algebra
Middle School Word Problems

Search the Dr. Math Library:


Find items containing (put spaces between keywords):
 
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________

Ask Dr. MathTM
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/