Expression

2y+3y

An equation without an equals sign

 in an algebraic expression, letters can stand for numbers
2x-1x

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http://en.wikipedia.org/wiki/Expression_(mathematics)

http://en.wikipedia.org/wiki/Expression

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http://voices.yahoo.com/teaching-math-expressions-11937926.html

http://www.icoachmath.com/math_dictionary/numerical_expression.html


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