Solving Inequalities with Rational Numbers

1
Solving Inequalities with
Rational Numbers
3-7
Warm Up
Problem of the Day
Lesson Presentation
Pre-Algebra
2
Warm Up Solve.
1. t 8.7 12.4
4 9
1 3
2. r

4
11
3. 3.2x 14.4
p 8.6
4. 5.4
3
Problem of the Day Arnie built a fence around a
rectangular field that measures 120 feet by 90
feet. He put a post in each corner and every 6
feet along all four sides. How many fence posts
did he use?
70 posts
4
Learn to solve inequalities with rational
numbers.
Math Fact Solving inequalities is almost
exactly like equations, except when dividing by a
negative.
5
Solve.
B. y 3.8 lt 11
A. 0.4x ? 0.8
3.8 3.8
y lt 14.8
x ? 2
6
Solve.
7
Solve.
n ? 4
8
Solve.
j 5
9
The height of an envelope is 4.9 in. What are the
minimum and maximum lengths to avoid an extra
charge?
With first-class mail, there is an extra charge
in any of the following cases
The height is greater than 6.125 inches The
thickness is greater than 0.25 inch The length
divided by the height is less than 1.3 or greater
than 2.5
10
4.9 1.3 l and l 2.5 4.9
6.37 l and l 12.25
11
The height of an envelope is 4.9 in. What are the
minimum and maximum lengths to avoid an extra
charge?
With first-class mail, there is an extra charge
in any of the following cases
6.37 l and l 12.25
The length of the envelope must be between 6.37
in. and 12.25 in.
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Lesson Quiz Part 1
Solve.
w 3.87
1. w 1.25 ? 5.12
1 4
3 8
2. f 1 ? 4

3. 1.2x gt 17.04
x gt 14.2
h 0.7
lt 5.5
4.
h lt 3.85
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Lesson Quiz Part 2
5.
Rosas car gets between 20 and 21 mi/gal on the
highway. She knows that her gas tank holds at
least 18 gallons. Using a full tank of gas, what
is the minimum distance Rosa could drive her car
on the highway between fill-ups?
360 miles
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Homework

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