Variables and Expressions

Variables and Expressions

Ms. Benavente

1st period

Key Vocabulary Terms

• Numerical Expression

• Variable

• Variable expression

• Evaluate

Expressions and Variables

• A numerical expression is an equation that has numbers and operations ONLY

• A variable is a letter of the alphabet that represents a number

• A variable expression is an equation that has numbers, variables, AND operations

• When you evaluate a variable expression, you are replacing the variable with the number.

Different types of variable expression & steps to EVALUATE a variable expression

Multiple Choice

What word means a letter that represents a number?

• variable

• numerical expression

• variable expression

• evaluate

Multiple Select

Click all that can be considered a NUMERICAL EXPRESSION

• 3 + 2

• 5x - 10

• 10x + 2

• 86 + 1020

Multiple Choice

When you evaluate a variable expression you are .....

• replacing the variable with a number

• looking at it

• answering it

• leaving it alone

Evaluate the expression to find out how many tons of food a blue whale eats in a feeding season of 120 days.

 $4\ \cdot\ d\ when\ d\ =\ 120$  

Evaluate the expression (continued)

 $4\cdot d$  

 $4\cdot120$        Substitute 120 for d

 $480$             Multiply 4 and 120 

Evaluate the expression when

x = 10  and y = 4

1.  $x\ +\ y$  

       10 + 4             Substitute 10 for x and 4 for y
        14                  Add

2.  $xy$  
       10 ( 4 )            Substitute 10 for x and 4 for y
       40                   Multiply

Multiple Choice

Evaluate the expression when y = 12

 $y+8$  

• 20

• 22

• 28

• 19

Multiple Choice

Evaluate the expression when x = 6

 $9\ -\ x$  

• 10

• 3

• 11

• 12

Multiple Choice

Evaluate the expression when x = 6 and y = 12

 $y-x$  

• 10

• 5

• 6

• 1

Multiple Choice

Evaluate the expression when x = 6 and y = 12

 $xy$  

• 72

• 90

• 100

• 81

Poll

How are you feeling about this lesson?

• I GET IT!

• Kind of get it

• HELP! I don't get it