CONFIDENTIAL 1

Warm-up:

1.) 98 - 12 =

2.) 49 + 13 =

3.) 9 - 6 ÷ 3 =

4.) 4 + 5 x 8 =

5.) 72 - 20 =

Today we will learn How to Evaluate Expressions

CONFIDENTIAL 2

Remember...

ORDER OF OPERATIONS

A set of rules that tells us which operation to perform first

We can recall the Order of Operations as P E M D A S

Parentheses

Exponents

Multiplication

Division

Addition

Subtraction

CONFIDENTIAL 3

P E M D A S

We multiply and divide in order from left to right.

THEN we add and subtract in order from left to right.

63 ÷ (10 - 3) x 3 + 6

63 ÷ 7 x 3 + 6

Do the Parentheses first

Then we Divide

9 x 3 + 6

Then we Multiply

Finally we Add27 + 6

32

CONFIDENTIAL 4

ALGEBRA is a mathematical language in whichsymbols represent numbers and they are related by operations.

We call the symbols "VARIABLES".

n

tx

p

"VARIABLES" are usually letters which

are used to represent Numbers.

qw

c

b

y

xt

h

w

d

f

z

u

k

l

x

t

q

m

h

s

s

CONFIDENTIAL 5

3 + n is an "ALGEBRAIC EXPRESSION"

Numbers

Operations

Variables

Algebraic Expressions consist of Numbers, Operations, and Variables.

CONFIDENTIAL 6

The VARIABLES in an expression can be replaced with any number.

3 + x

If I substitute a 5 for the x ...........

I have 3 + 5 or 8

This is how we Evaluate (or find the value of) the Expression

CONFIDENTIAL 7

Let's Evaluate the Algebraic Expression 16 + b if b = 25

We replace b with the number 25

16 + b = 16 + 25

= 41

The Value of the Algebraic Expression when b = 25 is 41

CONFIDENTIAL 8

Let's Evaluate the Algebraic Expression x - y if x = 64 and y = 27

In other words, in the Expression x - y , let's replace x with the number 64 and replace y with the number 27.

x - y = 64 - 27

= 37

CONFIDENTIAL 9

There are several ways to show multiplication.

2 3 means 2 x 3

6t means 6 x t

st means s x t

We always write thenumber BEFORE thevariable.

.

CONFIDENTIAL 10

Evaluate the expression 5t + 4 if t = 3

Replace t for the number 3

5t + 4 = 5 x 3 + 4

= 15 + 4 Remember PEMDAS!

= 19

CONFIDENTIAL 11

Your Turn!

Evaluate each expression if a = 6 and b = 4

1.) a + 8 =

2.) a - b =

3.) a x b =

4.) 2a - 5 =

CONFIDENTIAL 12

Complete the Table

Algebraic Expressions 7a - 3b 2w - 3x + 4y

Name the Variables

Name the Numbers

Name the Operations

(1) (2)

CONFIDENTIAL 13

Distance can be calculated using the formulaD = rt

where r = rate and t = time

Find the distance (D) from Dallas to Houston if Iam travelling in my car at a rate (r) of 60 miles per hourAND it take me 4 hours (t) without stopping.

D = r t

Remember that rt means r x t

D = r tD = 60 x 4

D = 240

That's 240 miles!

CONFIDENTIAL 14

Find the value of 2x2 - 6 x 2 if x = 7

First replace the x with the number 7

Remember PEMDAS and handle the exponents first.

Do the multiplication in the order in which it occurs.

Finally, do the subtraction.

CONFIDENTIAL 15

Which one of these expressions is NOT an Algebraic Expression?

1.) ab

2.) 16 + 3

3.) 3x + 2

4.) 7x

CONFIDENTIAL 16

1.) In the Algebraic Expression 3x + 5 - 2y

- what are the variables?

-what are the numbers?

-what are the operations?

Evaluate each expression if a = 3, b = 12, and c = 8.

2.) 7c ÷ 4 + 5a

3.) a2 + 5b - c2

4.) b2 ÷ ( 3 c)

5.) 15 + 9a ÷ 3

.

CONFIDENTIAL 17

Good Job! You worked hard today!

Let's review what we learned.....

Algebraic Expressions consist of Variables, Numbers, and Operations.

Example: 4x + 8

Variables are symbols (usually letters) that represent Numbers.Example: x or y or a or b etc.

The Variables in an Expression can be replaced with Numbers.Example: In the Expression 4b - 2 , we can replace b with a

Number.

We can Evaluate Expressions by finding the value of the Expressionwhen we replace the Variable with a Number.

Example: When b = 3, the Expression 3b +10 has a value of 19

We can write multiplication as 3 x a OR 3a OR 3 a

.