Parts of an Expression

What is Algebra? Rather than using words, algebra uses symbols to make statements about things. In algebra, we often use letters to represent numbers. Since algebra uses the same symbols as arithmetic for adding, subtracting, multiplying and dividing, you're already familiar with the basic vocabulary. In this lesson, you'll learn some important new vocabulary words, and you'll see how to translate from plain English to the "language" of algebra.

REVIEW Discuss some words that you already know for each of the following operations. ADD SUBTRACT MULTIPLY DIVIDE

Expression vs. Equation What is the difference between an expression and an equation? An expression A mathematical phrase involving at least one variable and sometimes numbers and operation symbols. Since it is a phrase (not a complete sentence),it does not include an equal sign. An equation is a sentence stating that two things are equal, so it does include an equal sign.

TERMS In an algebraic expression, terms are the elements separated by the plus or minus signs. Identify the number of terms in the following expressions: 3x2 + 4y – 2xy + 7 8x – 4 5xy 9x + 3y + 2

VARIABLES Terms may consist of variables, coefficients and constants. Variables are letters that represent numbers. The most common variables are x and y.

COEFFICIENTS Coefficients are the number part in front of the terms with variables. Identify the coefficient of the term 3x2.

CONSTANTS Constants are the terms in the algebraic expression that contain only numbers (or no variables). Identify the constant in the expression 3x2 + 4y – 2xy + 7.

FACTORS Factors are numbers and/or variables that are being multiplied together. For example, there are 3 factors in the term 4xy.

Evaluating Expressions You can evaluate expressions by plugging in the given values for each variable. a = 2, b = -3, c = 4 3a + b a2 – 4b + c b2 - c

Lesson Quiz Identify each part of the algebraic expression as the coefficient, constant or variable. 4x – 12 a + 3b 6y