Page 498 - Algebra 1

Example
4
Solving Disjunctions
Solve the disjunction x - 3 < -5 OR -2x < -6. SOLUTION
Solve the two inequalities separately.
x - 3 < -5 OR -2x < -6 x < -2 OR x > 3
The solution is x < -2 OR x > 3.
Writing a Compound Inequality from a Graph
Write a compound inequality that describes each graph.
a.
The compound inequality is -1 < x ≤ 5 or x > -1 AND x ≤ 5.
b.
-4 -2 0 2 4 6 SOLUTION
The compound inequality is x ≤ -2 OR x ≥ 4.
Write and graph a compound inequality to represent the statement.
(Ex 1)
a. all real numbers that are greater than 5 and less than 10
b. a recommended cooking time for lasagna from 16 minutes to 20 minutes
c. A cellular phone company has a policy that charges a monthly fee of
(Ex 2)
Write and graph a compound inequality to represent the statement.
(Ex 3)
d. all real numbers greater than 6 or less than 1
e. all real numbers greater than or equal to 5 or less than or equal to 0
f. Solve the disjunction 5x > -5 OR 6x < -18.
(Ex 4)
Write a compound inequality that describes each graph.
(Ex 5)
g.
-2 0 2 4 6 8 h.
4 6 8 10 12 14 16
Hint
Remember that dividing by a negative number in an inequality reverses the order of the inequality.
Math Reasoning
Justify Why is “all real numbers” the solution of the disjunction x > -2 OR x < 3?
Example
5
-4 -2 0 2 4 6 SOLUTION
Lesson Practice
$20 plus $0.05 per minute of usage or text message. The monthly cell phone bill must be between $40 and $50. Write a compound inequality that describes the situation. Solve the inequality to find the number of minutes that can be used to keep the monthly bill within the desired amounts.
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