11-7 Dividing Integers
Warm Up
Problem of the Day
Lesson Presentation
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11-7 Dividing Integers
Warm Up
Find each quotient.
1. 18 ÷ 2 9
2. 42 ÷ 7
6
3. 56 ÷ 8 7
4. 24 ÷ 6
4
5. 3,600 ÷ 4 900 6. 540 ÷ 60 9
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11-7 Dividing Integers
Problem of the Day
Hank wanted to record the number of
marbles he lost to his friend Marcus
each day for 5 days. He forgot to record
one day, but for the other days he wrote
8, 2, 3, and 4. The average number he
lost was 4. What number did he forget
to write?
3
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11-7 Dividing Integers
Learn to divide integers.
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11-7 Dividing Integers
Multiplication and division are inverse
operations. To solve a division problem,
think of the related multiplication.
Remember!
To find the mean of a list of numbers:
1. Add all the numbers together.
2. Divide by how many numbers are in the list.
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11-7 Dividing Integers
Additional Example 1: Dividing Integers
Find each quotient.
A. –30 ÷ 6
Think: What number times 6 equals –30?
–5
•
6 = –30, so –30 ÷ 6 = –5.
B. –42 ÷ (–7)
Think: What number times –7 equals –42?
6
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•
(–7) = –42, so –42 ÷ (–7) = 6.
11-7 Dividing Integers
Check It Out: Example 1
Find each quotient.
A. –15 ÷ 5
Think: What number times 5 equals –15?
–3
•
5 = –15, so –15 ÷ 5 = –3.
B. –36 ÷ (–6)
Think: What number times -6 equals –36?
6
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•
(–6) = –36, so –36 ÷ (–6) = 6.
11-7 Dividing Integers
Because division is the inverse of multiplication,
the rules for dividing integers are the same as the
rules for multiplying integers.
Dividing Integers
If the signs are the same, the product is positive.
24 ÷ 3 = 8
–6 ÷ (–3) = 2
If the signs are different, the quotient is negative.
–20 ÷ 5 = –4
72 ÷ (–8) = –9
Zero divided by any integer equals 0.
0
0
__
__
=0
=0
–11
14
You cannot divide any integer by 0.
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11-7 Dividing Integers
Additional Example 2A: Evaluating Integer
Expressions
d for each value of d.
Evaluate __
4
d = 16
d
__
4
16
__
= 16 ÷ 4
4
=4
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Write the expression.
Substitute 16 for d.
The signs are the same, so the
answer is positive.
11-7 Dividing Integers
Additional Example 2B: Evaluating Integer
Expressions
d for each value of d.
Evaluate __
4
d = –24
d
__
4
Write the expression.
-24
___
= –24 ÷ 4 Substitute –24 for d.
4
= –6
The signs are different, so the
answer is negative.
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11-7 Dividing Integers
Additional Example 2C: Evaluating Integer
Expressions
d for each value of d.
Evaluate __
4
d = –12
d
__
4
Write the expression.
-12
___
= –12 ÷ 4 Substitute –12 for d.
4
= –3
The signs are different, so the
answer is negative.
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11-7 Dividing Integers
Check It Out: Example 2A
c
Evaluate __ for each value of c.
3
c = –15
c
__
3
Write the expression.
-15
___
= –15 ÷ 3 Substitute –15 for c.
3
= –5
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The signs are different, so the
answer is negative.
11-7 Dividing Integers
Check It Out: Example 2B
c
Evaluate __ for each value of c.
3
c = 12
c
__
3
12
___
= 12 ÷ 3
3
=4
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Write the expression.
Substitute 12 for c.
The signs are the same, so the
answer is positive.
11-7 Dividing Integers
Check It Out: Example 2C
c
Evaluate __ for each value of c.
3
c = 27
c
__
3
27
__
= 27 ÷ 3
3
=9
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Write the expression.
Substitute 27 for c.
The signs are the same, so the
answer is positive.
11-7 Dividing
Insert Lesson
Integers
Title Here
Lesson Quiz
Find each quotient.
1. 18 ÷ (–3) –6
2. –36 ÷ (–6) 6
3. –64 ÷ (–8) 8
4. –45 ÷ 3
x
Evaluate __ for each value of x.
4
–15
5. x = –12 –3
5
6. x = 20
7. Carmen’s mom has $3,200 in her bank
account. If she uses the money to make
monthly rent payments of $375, how many
whole payments can she make? 8
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