Lesson 3: Evaluate algebraic expressions given variable values

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6/15/11
Lesson 3 Evaluate algebraic expressions given
variable values
2
6/15/11
Todays Agenda

• Review PEMDAS
• Example Problem
• Show common calculation errors
• Practice problems
• End-of-class assignment

3
Order of Operations
PEMDAS
lease
xcuse
y
ear
unt
ally
4
Order of Operations
PEMDAS
arentheses
xponent
ultiplication
ivision
ddition
ubtraction
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Order of Operations
PEMDAS
( )
72
x
-

-
6
6/15/11
Todays Agenda

• Review PEMDAS
• Example Problem
• Show common calculation errors
• Practice problems
• End-of-class assignment

7
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 1
Plug the variable values into the expression.
2
6
7x (12y)2 y (x1)
8
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 1
Plug the variable values into the expression.
72 (126)2 6 (21)
9
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 2
Evaluate the expression, using PEMDAS.
72 (126)2 6 (21)
Parentheses
10
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 2
Evaluate the expression, using PEMDAS.
72 (2)2 6 (3)
11
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 3
Evaluate the expression, using PEMDAS.
72 (2)2 6 3
Exponent
12
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 3
Evaluate the expression, using PEMDAS.
72 4 6 3
13
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 4
Evaluate the expression, using PEMDAS.
72 4 6 3
Multiply
14
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 4
Evaluate the expression, using PEMDAS.
14 4 6 3
15
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 4
Evaluate the expression, using PEMDAS.
14 4 6 3
No D left, so now simply Add and Subtract!
16
Order of Operations
PEMDAS
Practice Problem 1 Evaluate algebraic
expression given variable values
7x (12y)2 y (x1)
Expression
Given
x 2 and y 6
Step 5
Evaluate the expression, using PEMDAS.
18 6 3 ? 12 3 ? 9
The answer is 9
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6/15/11
Todays Agenda

• Review PEMDAS
• Example Problem
• Show common calculation errors
• Practice problems
• End-of-class assignment

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Remember

• M and D are together
• A and S are together
• Following PEMDAS
• Solve from left to right

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Common Mistakes
Example Expression WRONG! RIGHT!
Example 1 5 3 6 5 9 2 6
Example 2 10 8/2 2/2 10 4
Example 3 3 5(10 6) 8(10 6) 3 5(4)
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6/15/11
Todays Agenda

• Review PEMDAS
• Example Problem
• Show common calculation errors
• Practice problems
• End-of-class assignment

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Further Practice
Example 1 when m 2 and n 3
3m (n 1)
32 (3 1)
32 (4)
6 4
2
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Further Practice
Example 2 when q 1 and r 2
(4q r)2 1
(41 2)2 1
(4 2)2 1
22 1
4 1
3
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Any questions about the last two problems?
?
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6/15/11
Todays Agenda

• Review PEMDAS
• Example Problem
• Show common calculation errors
• Practice problems
• End-of-class assignment