# Week 6

Algebraic Expressions

**papadzulporrasespanola**

**Algebraic Expressions**

An algebraic expression is a mathematical expression that involves one or more variables. These variables are represented by certain letters.

So, for example, the number 6 is not a variable. It is a number, or what we might call a constant. Any number can be a constant, like 6, 5.2, negative 1, or one half.

A variable on the other hand, has a value that is never fixed, can change, and is represented by a letter. Common letters for variables are x, y, and z, well as a, b, and c and r, s, and t. But it can be any letter. The purpose of a variable is to generalize the result of an equation.

Then you have the algebraic operations, which are the standard operations we have covered in previous modules, namely addition, subtraction, multiplication and division.

Putting all these together then, if we have any constant and variable connected to an algebraic operation, then it is called an algebraic expression. So, for example, 4x + 9y + z. You could also just have a simple 4x and that would count as an algebraic expression. Or, you could have something more complicated, like 4x cubed plus the square root of z… But for now, just know that when you have variables, numbers, and operations, it is an algebraic expression.

**Evaluate Algebraic Expression**