1. Evaluate algebraic expressions given variable values
6/15/11
Lesson 3
Evaluate algebraic expressions given variable values

2. Today’s Agenda 6/15/11 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. PEMDAS Order of Operations arentheses xponent ultiplication ivision
ddition
ubtraction

5. Order of Operations
PEMDAS
( ) 72 x - + -

6. Today’s Agenda 6/15/11 Review PEMDAS Example Problem
Show common calculation errors
Practice problems
End-of-class assignment

7. Step 1: PEMDAS Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 1:
Plug the variable values into the expression. 2
7x + (12÷y)2 – y – (x+1) 6

8. Step 1: PEMDAS Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 1:
Plug the variable values into the expression.
7*2 + (12÷6)2 – 6 – (2+1)

9. Step 2: PEMDAS Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 2:
Evaluate the expression, using PEMDAS.
7*2 + (12÷6)2 – 6 – (2+1)
Parentheses

10. Step 2: PEMDAS Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 2:
Evaluate the expression, using PEMDAS.
7*2 + (2)2 – 6 – (3)

11. Step 3: PEMDAS Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 3:
Evaluate the expression, using PEMDAS.
7*2 + (2)2 – 6 – 3
Exponent

12. Step 3: PEMDAS Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 3:
Evaluate the expression, using PEMDAS.
7*2 + 4 – 6 – 3

13. Step 4: PEMDAS Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 4:
Evaluate the expression, using PEMDAS.
7*2 + 4 – 6 – 3
Multiply

14. Step 4: PEMDAS Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 4:
Evaluate the expression, using PEMDAS.
– 6 – 3

15. Step 4: PEMDAS Order of Operations
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 4:
Evaluate the expression, using PEMDAS.
– 6 – 3
No D left, so now simply Add and Subtract!

16. Step 5: PEMDAS The answer is 9 Order of Operations Expression:
Practice Problem #1: Evaluate algebraic expression given variable values
Expression:
7x + (12÷y)2 – y – (x+1)
Given:
x = 2 and y = 6
Step 5:
Evaluate the expression, using PEMDAS.
18– 6 – 3  12 – 3  9
The answer is 9

17. Today’s Agenda 6/15/11 Review PEMDAS Example Problem
Show common calculation errors
Practice problems
End-of-class assignment

18. Remember M and D are together A and S are together Following PEMDAS
Solve from left to right

19. Example Expression WRONG! RIGHT!
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)

20. Today’s Agenda 6/15/11 Review PEMDAS Example Problem
Show common calculation errors
Practice problems
End-of-class assignment

21. Further Practice
Example #1:
when m = 2 and n = 3
3m – (n + 1)
3*2 – (3 + 1)
3*2 – (4)
6 – 4 2

22. Further Practice
Example #2:
when q = 1 and r = 2
(4q – r)2 – 1
(4*1 – 2)2 – 1
(4 – 2)2 – 1
22 – 1
4 – 1 3

23. Any questions about the last two problems?

24. Today’s Agenda 6/15/11 Review PEMDAS Example Problem
Show common calculation errors
Practice problems
End-of-class assignment