An algebraic expression is a mathematical phrase that contains variables, numbers and operations. Examples of an algebraic expression include a + 1, 2 - b, 10y, and y + 6.
In an algebraic expression, a variable is defined as an alphabetical character. Typically, the first and last few letters of the alphabet are used: a, b and c, or x, y and z. The values of an algebraic expression change depending on the input value of the variable. The operations of an algebraic expression include addition, subtraction, multiplication and division. When an algebraic expression is defined as equaling a number or another algebraic expression, it is then defined as an equation. An example of an algebraic equation is X + 12 = 23, where X is in fact equal to 11.