Difference between revisions of "Equation"
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A unique aspect to equations is the ability to modify an original equation by performing operations (such as [[addition]], [[subtraction]], [[multiplication]], [[division]], and [[exponential function|powers]]). | A unique aspect to equations is the ability to modify an original equation by performing operations (such as [[addition]], [[subtraction]], [[multiplication]], [[division]], and [[exponential function|powers]]). | ||
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| + | It's important to note the distinction between an equation and an '''identity.''' An identity in terms of some [[variable]]s states that two expressions are equal for every value of those variables: for example, | ||
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| + | <math>x^2 - y^2 = (x - y)(x + y)</math> | ||
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| + | is an identity that is true regardless of the value of <math>x, y</math> (and indeed holds in a [[commutative]] [[ring]]). However, | ||
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| + | <math>x^2 = 4</math> | ||
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| + | is an equation that is true for a particular value of <math>x</math> which you may or may not wish to find. | ||
==See also== | ==See also== | ||
Revision as of 23:00, 23 April 2008
| This is an AoPSWiki Word of the Week for April 15-22 |
An equation is a relation which states that two expressions are equal, identical, or otherwise the same. Equations are easily identifiable because they are composed of two expressions with an equals sign ('=') between them.
Equations are similar to congruences (which relate geometric figures instead of numbers) and other relationships which fall into the category of equivalence relations.
A unique aspect to equations is the ability to modify an original equation by performing operations (such as addition, subtraction, multiplication, division, and powers).
It's important to note the distinction between an equation and an identity. An identity in terms of some variables states that two expressions are equal for every value of those variables: for example,
is an identity that is true regardless of the value of 
(and indeed holds in a commutative ring). However,
is an equation that is true for a particular value of 
which you may or may not wish to find.
See also
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