Holt CA Course 2

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Preview
Warm Up
Georgia Standards
Lesson Presentation
Holt CA Course 2
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EQ What are the rules for subtracting
integers? Warm Up Add the following 1. 7
2 4. 6 (28) 2. 12 (9) 5. 104
(87) 3. 32 (19) 6. 18 (24)
5
34
17
21
42
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Georgia Standards
M7N1 Add, subtract, multiply, and
divide rational numbers (integers, fractions, and
terminating decimals) and take positive rational
numbers to whole-number powers. Understand the
meaning of the absolute value of a number
interpret the absolute value as the distance of
the number from zero on a number line and
determine the absolute value of real numbers.

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When you subtract a positive integer, the
difference is less than the original number.
Therefore, you move to the left on the number
line. To subtract a negative integer, you move to
the right.
You can also subtract an integer by adding its
opposite. We also refer to this as keep, change,
change. You can then use the rules for addition
of integers.
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Additional Example 1 Subtracting Integers
Subtract.
A. 7 4
Add the opposite of 4. (Keep, change, change)
7 4 7 (4)
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Same sign use the sign of the integers.
B. 8 (5)
Keep, change, change.
8 (5) 8 5
Same sign use the sign of the integers.
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C. 6 (3)
Keep, change, change.
6 (3) 6 3
6 gt 3 use the sign of 6.
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Check It Out! Example 1
Subtract.
A. 3 (6)
3 (6) 3 6
Keep, change, change.
Same signs use the sign of the integers.
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B. 4 1
4 1 4 (1)
Keep, change, change.
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Same sign use the sign of the integers.
C. 7 (8)
Keep, change, change.
7 (8) 7 8
1
8 gt 7 use the sign of 8.
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Additional Example 2A Evaluating Expressions
with Integers
Evaluate the expression for the given value of
the variable.
9 y if y 4
9 y
9 (4)
Substitute 4 for y.
9 4
Keep, change, change.
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9 gt 4 use the sign of 9.
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Additional Example 2B Evaluating Expressions
with Integers
Evaluate the expression for the given value of
the variable.
n 6 for n 2
n 6
2 6
Substitute 2 for n.
2 (6)
Keep, change, change.
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Same sign use the sign of the integers.
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Additional Example 2C Evaluating Expressions
with Integers
Evaluate the expression for the given value of
the variable.
8 j 2 for j 6
8 j 2
8 (6) 2
Substitute 6 for j.
Keep, change, change.
8 6 2
14 2
8 6 14.
The absolute value of 14 is 14, and the absolute
value of 2 is 2. Add.
14 2
16
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Check It Out! Example 2A
Evaluate the expression for the given value of
the variable.
5 r for r 2
5 r
5 (2)
Substitute 2 for r.
5 2
Keep, change, change.
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5 gt 2 use the sign of 5.
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Check It Out! Example 2B
Evaluate the expression for the given value of
the variable.
a 7 for a 9
a 7
9 7
Substitute 9 for a.
9 (7)
Keep, change, change.
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Same sign use the sign of the integers.
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Check It Out! Example 2C
Evaluate the expression for the given value of
the variable.
11 m 7 for m 3
11 m 7
11 (3) 7
Substitute 3 for m.
Add the opposite of 3.
11 3 7
14 7
11 3 14.
The absolute value of 14 is 14. Add.
14 7
21
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Additional Example 3 Architecture Application
The top of the Sears Tower, in Chicago, is 1454
feet above street level, while the lowest level
is 43 feet below street level. How far is it from
the lowest level to the top?
Subtract the lowest level from the top.
1454 (43)
Keep, change, change.
1454 43
Same sign use the sign of the integers.
1497
It is 1497 feet from the lowest level to the top.
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Check It Out! Example 3
The distance from the high dive to the swimming
pool is 10 feet. The pool is 12 feet deep. What
is the total distance from the high dive to the
bottom of the pool?
Subtract the depth of the pool from the height of
the high dive.
10 (12)
10 12
Keep, change, change.
22
Same sign use the sign of the integers.
It is 22 feet from the diving board to the bottom
of the pool.
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Lesson Quiz
Subtract.
1. 6 (4)
2. 3 3
3. 4 (5)
2
6
9
Evaluate each expression for the given value of
the variable.
4. 9 s if s 5
14
5. 4 w 5 if w 21
20
6. Suretta is flying in an airplane and rises an
additional 20 feet. Then she descends 190 feet
toward the ground. How far below her original
height did Suretta go?
170 feet