Warm Up

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Preview
Warm Up
California Standards
Lesson Presentation
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Warm Up Simplify. 1.
2. 3. Write
each decimal as a fraction in simplest form. 4.
1.15 5. 0.22
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Additional Example 1 Adding and Subtracting
Decimals
Add or subtract.
A. 0.3 (1.2)
Think Find the difference of 1.2 and 3.
0.9

1.2 is greater than 0.3 use the sign of 1.2.
B. 17.2 4.39
Line up the decimal points. Use a zero as a
placeholder.
17.20
4.39
Subtract.
12.81
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Check It Out! Example 1
Add or subtract.
A. 0.4 2.2
Line up the decimal points.
0.4
2.2
Add.
2.6
B. 12.4 3.29
Line up the decimal points. Use a zero as a
placeholder.
12.40
3.29
Subtract.
9.11
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Additional Example 2 Sports Application
In August 2001, at the World University Games in
Beijing, China, Jimyria Hicks ran the 200-meter
dash in 24.08 seconds. Her best time at the U.S.
Senior National Meet in June of the same year was
23.35 seconds. How much faster did she run in
June?
Line up the decimal points.
0.73
She ran 0.73 second faster in June.
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Check It Out! Example 2
Tom ran the 100-meter dash in 11.5 seconds last
year. This year he improved his time by 0.568
seconds. How fast did Tom run the 100-meter dash
this year?
Subtract 0.568 from 11.5 to determine the new
time.
Add two zeros so the decimals align.
11.5
00
0.568
10.932
Tom ran the 100-meter dash in 10.932 seconds this
year.
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Subtracting a number is the same as adding its
opposite.
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Additional Example 3 Adding and Subtracting
Fractions with Like Denominators
Add or subtract. Write each answer in simplest
form
Subtract numerators. Keep the denominator.
A.
6 7
3 7
B.

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Check It Out! Example 3
Add or subtract. Write each answer in simplest
form
Subtract numerators. Keep the denominator.
A.
5 9
4 9
B.

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Additional Example 4A Evaluating Expressions
with Rational Numbers
Evaluate the expression for the given value of
the variable.
12.1 x for x 0.1
12.1 (0.1)
Substitute 0.1 for x.
12.2
Think 12.1 (0.1) 12.1 0.1
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Additional Example 4B Evaluating Expressions
with Rational Numbers
Evaluate the expression for the given value of
the variable.
Add numerators, keep the denominator.
Simplify.
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Check It Out! Example 4A
Evaluate the expression for the given value of
the variable.
52.3 y for y 7.8
Substitute 7.8 for y.
52.3 (7.8)
Think 52.3 (7.8) 52.3 7.8
60.1
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Check It Out! Example 4B
Evaluate the expression for the given value of
the variable.
Add numerators, keep the denominator.
Simplify.
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Lesson Quiz
Add or subtract.
1. 1.2 8.4
2. 2.5 (2.8)
0.3
7.2
3.
Evaluate.
4. 62.1 x for x 127.0
64.9
5.
Sarahs best broad jump is 1.6 meters, and Jills
best is 1.47 meters. How much farther can Sarah
jump than Jill?
0.13 m