Question 55·Easy·Linear Inequalities in One or Two Variables
Which of the following values of satisfies the compound inequality
?
For compound inequalities like , treat them as three-part inequalities and perform the same operation on all three parts step by step. First eliminate constants (like subtracting 6), then isolate (by dividing), remembering to flip the inequality signs only if you multiply or divide by a negative. Once you have a final interval for , quickly compare each answer choice to that interval, which is usually faster and less error-prone than plugging each choice directly into the original inequality.
Hints
See the structure of the inequality
Notice that is a three-part inequality. Think of it as saying must be greater than and at the same time less than or equal to .
Isolate the expression with
Try to isolate step by step. What operation will remove the from the middle expression ? Make sure you apply that operation to all three parts of the inequality.
Finish solving for
After you remove the , you will have something like a number or or another number. What should you divide by to get alone, and do you need to flip the inequality signs?
Use the final interval to test choices
Once you have an interval for (like ), check each answer choice against that interval. Pay close attention to which endpoint is strict () and which is inclusive ().
Desmos Guide
Graph the expression as a function
In Desmos, enter the equation y = 2x + 6. This shows the line representing for all .
Add the boundary lines for the inequality
Enter y = -4 and y = 10 as two more equations. These horizontal lines represent the lower and upper bounds for in the inequality .
Use a table to test the answer choices
Click on the y = 2x + 6 equation and add a table. In the -column, type the four answer choices: , , , and . Look at the corresponding -values in the table and check which row has a -value that is greater than and less than or equal to . The in that row is the value that satisfies the compound inequality.
Step-by-step Explanation
Understand the compound inequality
The inequality
is a compound inequality, meaning must be greater than and less than or equal to at the same time. We will solve it as a three-part inequality to find all possible values.
Subtract 6 from all three parts
To isolate , first get rid of the by subtracting from every part of the inequality:
which simplifies to
The inequality signs stay the same because we are just subtracting a number.
Divide all three parts by 2
Now divide every part by to solve for :
which simplifies to
We do not flip the inequality signs because we are dividing by a positive number.
Compare the solution interval to the answer choices
The solution set is all real numbers such that
Now check each answer choice:
- is not greater than .
- and are greater than .
- is greater than and less than or equal to .
So the only value that satisfies the compound inequality is (choice B).