Jack is 3 years older than his brother. How old are they if the sum of their ages is greater than 17? Write an inequality and solve. Represent the solution set on a number line.
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Khan Academy Inequalities on a Number Line
Guidance
When you solve a linear inequality you can represent your solution graphically with a number line. Your job is to show which of the numbers on the number line are solutions to the inequality.
When graphing solutions to inequalities, use an open circle to show that the number is not included as part of the solution and a closed circle to show that the number is included as part of the solution. The line above the number line shows all of the numbers that are possible solutions to the inequality.
Example A
Represent the solution set to the following inequality on a number line: .
Solution:
Example B
Represent the solution set to the following inequality on a number line: .
Solution:
Example C
Represent the solution set to the following inequality on a number line: .
Solution:
Concept Problem Revisited
Jack is 3 years older than his brother. How old are they if the sum of their ages is greater than 17? Write an inequality and solve. Represent the solution set on a number line.
If first let’s write down what you know:
Let Jack’s brother’s age
Let Jack’s age
The equation would therefore be:
Therefore if Jack’s brother is 8 (since ), Jack would be 11. If Jack's brother is 10, Jack would be 13.
Representing Jack's brother's age on a number line:
Vocabulary
- Number Line
- A number line is a line that matches a set of points and a set of numbers one to one.
Guided Practice
1. Represent the solution set to the inequality on a number line.
2. Represent the solution set to the inequality on a number line.
3. Represent the solution set to the inequality on a number line.
Answers:
1.
2.
3.
Practice
Solve each inequality and represent the solution set on a number line.
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