Lesson 1.1 Expressions and Variables

Objective and Essential Question

By the end of this lesson, you will be able to answer the question: How do you write and solve variable expressions?

Key Vocabulary Numerical Expression: consists of numbers and

operations

Variable: a variable used to represent one or more numbers

Variable expression: consists of numbers variables and operations

Evaluate: to find the value of a numerical or algebraic expression

Example 1Evaluate the expression when d= 120 to find

about how many tons of food a blue whale eats in a feeding season of 120 days.

Example 2 Evaluate the expression when x=10 and y=4

A. x+y

B. xy

Example 3 You plan to divide the 120 players in a

baseball league into teams with the same number of players. Use a verbal model to write a variable expression for the number of teams if you know the number of players on each team.