VARIABLES & EXPRESSIONSSection 1.1

Quantity• Anything that can be measured or counted

Variable• A symbol, usually a letter, that represents the value(s) of a

quantity whose value can vary or change.

How is an algebraic expression different from a numerical expression?

Algebraic Expression:

Mathematical phrase that includes one or more variables.

Numerical Expression:

Mathematical phrase involving numbers and operation symbols, but no variables.

Words that tell you to add….

Words that tell you to subtract…

Multiply and Divide Words…..

Write the mathematical statement for the following…..• 9 increased by 2

• 5 decreased by m

• Sum of 4 and 2x

Write the mathematical statement for the following…..

• 7 less than 12

• 7 increased by 5 times a number

Write the mathematical statement for the following…..

• 8 decreased by 3 times a number

• The sum of twice a number and 5

Write the mathematical statement for the following…..

• The product of 4 and the sum of a number and six.

• Eight less that the quotient of ten and two

You Try…..

• The sum of 7 and 3 times a number

• 4 times Harry’s age increased by 2

• 8 pounds less than twice wanda’s weight

You Try…..

• Eight more than the sum of twice a number and three.

• Four less than the product of five and a numbers

• Six times the sum of a number and five.

Let’s play!

• http://www.math-play.com/Algebraic-Expressions-Millionaire/algebraic-expressions-millionaire.html

How can you represent the following algebraic expressions?

𝑥+7 Seven more than a number

How can you represent the following algebraic expressions?

2 𝑥+5 Five more than twice a number

How can you represent the following algebraic expressions?

𝑛−4 Four less than a number

How can you represent the following algebraic expressions?

5 𝑥−1 One less than the product of five and a number

How can you represent the following algebraic expressions?

𝑥2

The quotient of a number and two.

Let’s play

• http://www.math-play.com/Algebraic-Expressions-Millionaire/algebraic-expressions-millionaire.html

The table below shows how the height above the floor of a house of cards depends on the number of levels. What is a rule for the height?

# Levels Height (n)

2  

3  

4  

n  

Suppose you draw a segment from any one vertex of a regular polygon to the other vertices. Use the table to find a pattern and state the rule.

#SidesNumber of Triangles

4 4 – 2

5 5 – 2

6 6 – 2

n  

Homework

• Worksheet