hw: page 10 #5-18 answers. agenda: 6 th gr. math: 1-3 hw page 14 #10-24 all
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1-3 Exponents
Course 1
Warm UpWarm Up
Lesson PresentationLesson Presentation
Problem of the DayProblem of the Day
Problem of the Day
Replace the letters a, b, and c with the numbers 3, 4, and 5 to make a true statement.2a + 2a = bc
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25+ 25 = 43
Today’s Learning Goal (8/15/2012)
Learn to represent numbers by using exponents.
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A number is in exponential form when it is written with a base and an exponent.
7733Base
Exponent
= 7 7 7= 343
An exponent tells how many times a number called the base is used as a factor.
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1-3 Exponents
Exponential Form 102
Read“10 squared” or “10 to the 2nd power”
Multiply 10 10
Value 100
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Exponential Form 103
Read“10 cubed” or “10 to the 3rd power”
Multiply 10 10 10
Value 1,000
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Exponential Form 104
Read “10 to the 4th power”
Multiply 10 10 10 10
Value 10,000
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Additional Example 1: Writing Numbers in Exponential Form
Write each expression in exponential form.
A. 5 5 5 5
B. 3 3 3 3 3
5 is a factor 4 times.54
3 is a factor 5 times.35
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Try This: Example 1
Write each expression in exponential form.
A. 7 7 7
B. 6 6 6 6 6 6
7 is a factor 3 times.73
6 is a factor 6 times.66
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Additional Example 2: Finding the Value of Numbers in Exponential Form
Find each value.
A. 26
B. 45
26
45
= 2 2 2 2 2 2
= 64
= 4 4 4 4 4
= 1,024
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Try This: Example 2
Find each value.
A. 34
B. 25
34
25
= 3 3 3 3
= 81
= 2 2 2 2 2
= 32
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A phone tree is used to contact families at Paul’s school. The secretary calls 4 families. Then each family calls 4 other families, and so on. How many families will notified during the fourth round of calls?
11 Understand the Problem
The answer will be the number of families called in the 4th round.
List the important information:
• The secretary calls 4 families.
• Each family calls 4 families.
Additional Example 3: Problem Solving Application
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You can draw a diagram to see how many calls are in each round.
22 Make a Plan
Secretary
1st round – 4 calls
2nd round–16 calls
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Solve33Notice that in each round, the number of calls is a power of 4.
1st round: 4 calls = 4 = 41
2nd round: 16 calls = 4 x 4 = 42
So during the 4th round, there will be 44 calls. 44 = 4 4 4 4 = 256
During the 4th round of calls, 256 families will have been notified.
Look Back44Drawing a diagram helps you see how to use exponents to solve the problem.
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1-3 Exponents
Try This: Example 3
A phone tree is used to contact families at Paul’s school. The secretary calls 3 families. Then each family calls 3 other families, and so on. How many families will notified during the fourth round of calls?
11 Understand the Problem
The answer will be the number of families called in the 3rd round.
List the important information:
• The secretary calls 3 families.
• Each family calls 3 families.
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1-3 Exponents
You can draw a diagram to see how many calls are in each round.
22 Make a Plan
Secretary
1st round – 3 calls
2nd round–9 calls
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Solve33Notice that in each round, the number of calls is a power of 3.
1st round: 3 calls = 3 = 31
2nd round: 9 calls = 3 x 3 = 32
So during the 4th round, there will be 34 calls. 34 = 3 3 3 3 = 81
During the 4th round of calls, 81 families will have been notified.
Look Back44Drawing a diagram helps you see how to use exponents to solve the problem.
Lesson Quiz
Write each expression in exponential form.
1. 12 12 12
2. 9 9 9 9 9 9 9
Find each value.
3. 202 4. 64
5. In a phone tree, each of three people will call
three people, and then each of those will call
three more. If there are five levels of the tree,
how many people will be called?
97
123
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400 1,296
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243
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