Lesson 1.1 Expressions and Variables Essential Question: How do you evaluate and write variable expressions?

Before we start… Look at the two items below. Tell your partner the difference.

What is a numerical expression? Consists of numbers and operations

What is a variable? A letter used to represent one or more numbers. The letter x is frequently used. – Often the variable used has a connection to the quantity it represents.

What is a variable expression? Consists of numbers, variables, and operations. The numbers are always written in front of the variable.

Variable Expression MeaningOperation 5(n) 5 ·n 5n 5 times nMultiplication 14  y 14/y 14 divided by yDivision 6 + c6 plus cAddition 8 – x8 minus xSubtraction

What does evaluating an expression mean? To substitute a number for each variable and calculate the resulting numerical expression. The final answer is a number!

How do you evaluate a variable expression? Substitute the number for the variable. Perform the operation(s). Simplify the result, if necessary.

How can we use expressions? You can solve real world problems using a verbal model to write a variable expression. A verbal model describes a problem using words as labels and using math symbols to relate the words.

How can we translate from words to expressions? To translate from words to expressions we want to look for words that indicate mathematical operations.

Translating Verbal Phrases Common Words and Phrases that Indicate Operations AdditionSubtractionMultiplicationDivision Plus The sum of Increased by Total More than Added to Minus The difference of Decreased by Fewer than Less than Subtracted from Times The product of Multiplied by Of Divided by Divided into The quotient of Order is IMPORTANT when writing subtraction and division expressions.

Write a variable expression to represent the phrase. The product of 72 and a number The difference of a number and 1

Write a variable expression to represent the phrase. The quotient of a number and 3 13 more than a number

Write a variable expression to represent the phrase. 6 fewer than a number A number multiplied by 12

Baseball You plan to divide the 120 players in a baseball league into teams with the same number of players. Write a variable expression for the number of teams if you know the number of players on each team.

Vegetables You plan to provide 8 carrot sticks for each of the hikers to take as a snack. Write a variable expression for the number of carrot sticks you will need if you know the number of hikers.

Shirts You buy 5 shirts each having the same price. Write a variable expression for the total amount you spend on the shirts. How much money do you spend on the shirts when each shirt costs $15?

Fundraiser Your school is organizing a fundraiser. Each student is asked to sell gift baskets for $15 and candles for $1. The table shows the items sold by 3 students. a.Write a variable expression for the total amount a student received by selling g gift baskets and c candles. b.Find the total amount received by each student. StudentNumber of Gift BasketsNumber of Candles Sally1863 Steven1333 Rose2460

How do you evaluate and write variable expressions?

Ticket Out the Door Evaluate the expression on a piece of paper (put your name on it) and place it in the box on your way out…