Algebra Key Vocabulary

Algebra Key Vocabulary

Students need to know certain algebra key vocabulary. This is a key issue that hurts a student’s chance for passing algebra. There are several misunderstandings about algebra vocabulary. The following list are the major areas of concern that if a student knows these definitions it will ensure that they can pass algebra.


Algebra - Algebra is doing arithmetic with at least one number replaced by a letter (normally X), which is referred to as an unknown and can be either a variable or a constant. For example, you know how to do 4 + 3 = 7. This is arithmetic. If we replace 3 with x we have 4 + x = 7. We know just from looking at this that x = 3. Algebra is provides the rules to find out the value of x.

Algebra Equations

Algebra Equations - An arithmetic or algebra equation is simply an arithmetic or algebra expression with an = sign. For example the arithmetic equations 4 + 2 = 6 or 4 * 5 = 20 and the algebra equations 4 + x =5 or 4 * x = 20.

Algebra Expressions

Algebra Expressions - An arithmetic expression is a sequence of numbers and operations such as 4 + 2 or 4 * 5 or 7 / 3. (Note that we DO NOT use the symbol x to indicate multiplication because in algebra x is frequently used as an unknown or variable). An algebra expression is a sequence of numbers, letters and operations such as 5+x or 7 * x or x / 4.


Binomials - Binomials are algebra expressions with only two terms, such as (x + 7) or (y – 15) for addition and subtractions operations only.

Completing the Square

One of the four methods of solving Quadratic Equations. Completing the Square is a method in which terms are added to both sides of the general Quadratic Equation ax^2+ bx + c = 0 where a, b and c are constants, such that the resulting expression on the left side is the resultant perfect square of a binomial. In other words, the result gives a perfect square trinomial that when factored is a perfect square.

Example: x^2-8x+16=0

; (x-4) (x-4) =0

Domain (All the X-Values)

The domain of a function consists of all real values of x that yields real values of y when the domain values of x are substituted for into the function. The domain is all the values of x (input) values for a function.


In arithmetic an exponent is represented by a base number with a super scripted number such as 4^3

The base number in this case is 4 and the exponent is 3. The exponent is the number of times the base is multiplied by itself. In our example 4^3 = 4 * 4 * 4 = 64. In Algebra, the base is usually an unknown or a variable such as x. In this case our equation would become x^3 = x * x * x.

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