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Elementary Algebra
Theory Refresher
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A variable is a letter that stands in place of a
number in an expression, which is called an algebraic expression.
The variable can take on many different values and is sometimes
called an unknown.
In algebraic expressions, multiplication signs are left out
and division is usually written as a fraction. Products and
fractions are considered the terms of the algebraic
expression. Terms are joined together by addition and subtraction.
Terms that have exactly the same variables are called like
terms and these can be added or subtracted together.
When multiplying two expressions that contain numbers and
variables, multiply the numbers together and write the variables
without any multiplication signs. Repeated variables incur
indices, that is, if each expression contains the same variable,
the result contains that variable squared.
When simplifying fractions, only factors that appear in every
single term in the fraction can be cancelled out.
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