2 Chapter Chapter 2 Integers and Introduction to Variables

Introduction to Variables and Algebraic Expressions Section 2.1 Introduction to Variables and Algebraic Expressions

Evaluate Algebraic Expressions Given Replacement Values. Objective A Evaluate Algebraic Expressions Given Replacement Values.

Algebraic Expressions A variable is a letter used to represent any number. A constant is either a fixed number or a letter that represents a fixed number. An algebraic expression is formed by numbers and variables connected by the operation of addition, subtraction, multiplication, division, raising to powers, and/or taking roots.

Terms Definitions Variable: A letter to represent all the numbers fitting a pattern. Algebraic Expression: A combination of numbers, letters (variables), and operation symbols. Evaluating the Expression: Replacing a variable in an expression by a number and then finding the value of the expression. Objective A Continued

Evaluating Expressions Example Evaluating Expressions Evaluate 7 + 3z when z = –3 Objective B

Evaluating Expressions Example Evaluating Expressions Evaluate 2(x – y) for x = 8 and y = 4 Objective B

Translate Phrases into Variable Expressions. Objective B Translate Phrases into Variable Expressions.

Translating Phrases sum plus added to more than increased by total Addition (+) Subtraction (–) Multiplication (·) Division () sum plus added to more than increased by total difference minus subtract less than decreased by less product times multiply multiplied by of double/triple quotient divide shared equally among per divided by divided into Objective A

Example Write as an algebraic expression. Use x to represent “a number.” a.) 5 decreased by a number b.) The quotient of a number and 12 a.) 5 decreased by a number – 5 x Objective A The quotient of b.) a number and 12 x  12