Basic Math and Pre-Algebra Workbook For Dummies, 2nd Edition

Chapter 14

Expressing Yourself with Algebraic Expressions

In This Chapter

Evaluating algebraic expressions

Breaking an expression into terms and identifying like terms

Applying the Big Four operations to algebraic terms

Simplifying and FOILing expressions

In arithmetic, sometimes a box, a blank space, or a question mark stands for an unknown number, as in , 9 –_____ = 5, or ? × 6 = 18. But in algebra, a letter such as x stands for an unknown number. A letter in algebra is called a variable because its value can vary from one problem to the next. For instance, in the equation 10 – x = 8, x has a value of 2 because 10 – 2 = 8. But in the equation 2(x) = 12, x has a value of 6 because 2 × 6 = 12.

Here are a few algebra conventions you should know:

• Multiplication: When multiplying by a variable, you rarely use the multiplication operator × or ·. As in arithmetic, you can use parentheses without an operator to express multiplication. For example, 3(x) means 3 × x. Often, the multiplication ...