# Pre-Algebra Lesson 3-8

Document Sample

3-8 Applying Equations and
Inequalities

Objective: Solve verbal problems by
translating them into equations and
inequalities, and write verbal problems for
equations and inequalities.
5-Minute Check

Solve each inequality and check the solution. Then graph the
solution on a number line.
1. –2x > 4
5-Minute Check

Solve each inequality and check the solution. Then graph the
solution on a number line.
1. –2x > 4            x < -2
5-Minute Check

Solve each inequality and check the solution. Then graph the
solution on a number line.
1. –2x > 4

2. 3x < -15
5-Minute Check

Solve each inequality and check the solution. Then graph the
solution on a number line.
1. –2x > 4

2. 3x < -15           x < -5
5-Minute Check

Solve each inequality and check the solution. Then graph the
solution on a number line.
1. –2x > 4

2. 3x < -15

x/
3.        (-4)  0
5-Minute Check

Solve each inequality and check the solution. Then graph the
solution on a number line.
1. –2x > 4

2. 3x < -15

x/
3.        (-4)  0      x0
5-Minute Check

Solve each inequality and check the solution. Then graph the
solution on a number line.
1. –2x > 4

2. 3x < -15

x/
3.        (-4)  0

4. 6  x/3
5-Minute Check

Solve each inequality and check the solution. Then graph the
solution on a number line.
1. –2x > 4

2. 3x < -15

x/
3.        (-4)  0

4. 6  x/3              x  18
3-8 Applying Equations and
Inequalities
Example
Ron is trying to budget his money this holiday season. He
wants to spend no more than \$100 for presents. If he buys
presents totaling \$85 and has one more present to buy, how
much can he spend?
3-8 Applying Equations and
Inequalities
Example
Ron is trying to budget his money this holiday season. He
wants to spend no more than \$100 for presents. If he buys
presents totaling \$85 and has one more present to buy, how
much can he spend?

Explore
You know how much Ron wants to spend and how
much he has already spent. You want to find out how much
money Ron can spend on the last present and stay on his
budget.
3-8 Applying Equations and
Inequalities
Example
Ron is trying to budget his money this holiday season. He
wants to spend no more than \$100 for presents. If he buys
presents totaling \$85 and has one more present to buy, how
much can he spend?

Plan
Translate the words into an equation. Let p represent the
cost of the last present.
last present plus \$85 equals no more than \$100
p     + 85 =                      100
3-8 Applying Equations and
Inequalities
Example
Ron is trying to budget his money this holiday season. He
wants to spend no more than \$100 for presents. If he buys
presents totaling \$85 and has one more present to buy, how
much can he spend?

Solve
p + 85 100
3-8 Applying Equations and
Inequalities
Example
Ron is trying to budget his money this holiday season. He
wants to spend no more than \$100 for presents. If he buys
presents totaling \$85 and has one more present to buy, how
much can he spend?

Solve
p + 85 100
p + 85 – 85 100 – 85
3-8 Applying Equations and
Inequalities
Example
Ron is trying to budget his money this holiday season. He
wants to spend no more than \$100 for presents. If he buys
presents totaling \$85 and has one more present to buy, how
much can he spend?

Solve
p + 85 100
p + 85 – 85 100 – 85
p  15
3-8 Applying Equations and
Inequalities
Example
Ron is trying to budget his money this holiday season. He
wants to spend no more than \$100 for presents. If he buys
presents totaling \$85 and has one more present to buy, how
much can he spend?

Examine
the total cost of the presents be less than or equal to \$100?
\$15 + \$85 ? \$100
\$100 = \$100 
Ron can spend no more than \$15 on the last present.
3-8 Applying Equations and
Inequalities
Integration: James scored 88 on his first test. He has another
test on Friday. What does he need to score on the second test if
he wants his average to be at least 93?
3-8 Applying Equations and
Inequalities
Integration: James scored 88 on his first test. He has another
test on Friday. What does he need to score on the second test if
he wants his average to be at least 93?
3-8 Applying Equations and
Inequalities
Integration: James scored 88 on his first test. He has another
test on Friday. What does he need to score on the second test if
he wants his average to be at least 93?

Answer: James must get a 98 or higher on the second test.
3-8 Applying Equations and
Inequalities
Assignment:
3-8 Applying Equations and
Inequalities
Assignment: 8 – 16 even, 17, 18, 20, 22 –
31 all
Starting on page: 158
3-8 Applying Equations and
Inequalities
Assignment:
3-8 Applying Equations and
Inequalities
Assignment: 8 – 16 even, 17, 18, 20, 22 –
31 all
Starting on page: 158
3-8 Applying Equations and
Inequalities
Assignment:
3-8 Applying Equations and
Inequalities
Assignment: 8 – 16 even, 17, 18, 20, 22 –
31 all
Starting on page: 158

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