What you should learn

To use the order of operations to evaluate real number expressions

NCTM Curriculm Standards 2 - 4, 6 - 9

 

In doing this the teacher wants to make sure that the following words are incorporated into the introductory lesson:

Order of Operations

Introduction: Bobbie Jackson is investing money in stocks to help pay for her child's college education. She buys one share of Kein stock at $16. She also purchases five shares of Tainer stock at $35 each. The expression below represents the amount of money Ms. Jackson spends for the stock purchase.

Numerical and algebraic expressions often contain more than one operation. A rule is needed to let you know which operation to perform first. This rule is called the order of operations.

To find the total amount of money Ms. Jackson invests, evaluate the expression 16 + 5 * 35. Which of the following methods is correct?

Method 1:

Method 2:

The answers are not the same because a different order of operations was used in each method. Since numerical expressions must have only one value, the following opder of operations has been established.

Order of Operations

1. Simplify the expressions inside grouping symbols, such as parentheses, brackets, and braces, and as indicated by fraction bars.

2.Evaluate all powers

3. Do all multiplications and divisions from left to right

4. Do all additions and subtractions form left to right

Based on the context of the problem and the order of operations, Method 1 is correct. Therefore, Ms. Jacvkson invested 16 + 5 * 35 or $191 in the stock market.

Other expressions can be evaluated by using the order of operations.

Exercise 1: Evaluate 5 * 7 - 6 2 +

Evaluate 5 * 7 - 6 2 + = 5 * 7 - 6 2 + 9 = 35 - 3 + 9 = 41

Exercise 2: Evaluate 8[ - 3(2 + 5)]8 + 3

Evaluate this expressions and your answer should be 18

Exercise 3: The figure below is a rectangle

a. Find the perimeter of the rectangle when s = 5

b. Find the area of the rectangle

Activity: Exploration: Graphing Calculators

You can use a graphing calculator to evaluate algebraic expressions. Use a calculator to evaluate when x = 0.75

ENTER: .75 : ( .25 ) ( 7 ^ 3 ) 0.0476190476

 

Your Turn

a. Evaluate the expression when x = 24.076

b.Evaluate when x = 27.89

c.Work through some of the examples in this lesson using a graphing calculator.

Closing Activity: Check for understanding by using this as a quick review before class is over. It should take about the last five to ten minutes. I would use it for my students as their 'ticket out the door'. Click Here.

Homework: The homework to be assigned for tonight would be: 13 - 41 odd, 42, 43, 45, 46 - 53

Alternative Homework: Enriched: 14 - 40 even, 42 - 53

Extra Practice: Students book page 756 Lesson 1-3

Extra Practice Worksheet: Click Here.

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