Download Inequalities - Ridgefield School

Name __________________
Section 5.3 Inequalities
Objectives:
1. Write Inequalities
2. Graph inequalities on a number line
Review:
 Solve and graph
each equation on a
number line.
x 5  3
x
Inequalities:
Steps:
1. Solve the inequality the same way you
would solve an equation.
2. Check the solution by plugging in a
number greater than the result and a
number less than the result.
3. Mark the result on the number line with
either a solid dot or an open circle.
4. Shade either to the left or the right.
Write Inequalities
 An inequality is a mathematical sentence
that compare quantities that are not
equal.
 Inequalities contain the symbols <, >, <,
or >
Examples
 Write an inequality for each sentence
 1. The DVD costs more than $15
 2. The speed limit is less than or equal to
35 miles per hour.
Practice
 3. A student must have at least 10 hours
of instructor assisted driving time to pass
the course. Write an inequality to
describe this situation.
 4. You must be at least 18 years old to
vote. Write an inequality to describe this
situation.
Notes
 Inequalities with variables are open
sentences. When the variable in an open
sentence is replaced with a number, the
inequality may be true or false.
Examples
 For the given value, state whether each
inequality is true or false.
 1. 2t + 8 > 7; t=1
 2. p – 42 < -2; p=40
Graph Inequalities
 Inequalities can be graphed on a number
line.
 The graph helps you visualize the values
that make the inequality true.
Open and Closed Dots
 When graphing inequalities, an open dot
is used when the value should not be
included in the solution, as with > and <
inequalities.
 A closed dot indicates the value is
included in the solution, as with < and >
inequalities.
Examples
 Graph each inequality on a number line.
 1. a > 6
 2. x > -2
Problem Solving
 Write an inequality for each sentence.
 1. The elevators in an office building have
been approved for a maximum load of
3600 pounds.
 2.Children under the age of 2 fly for free.
Essential Question
 Explain when you would use an open
circle and a closed circle when graphing
inequalities.
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