Chapter 2: Problem 28
Solve each inequality. Write the solution set in interval notation and graph it. $$ -\frac{7}{8} x \leq 21 $$
Short Answer
Expert verified
\([-24, \infty)\)
Step by step solution
01
Isolate the Variable
The inequality to solve is \(-\frac{7}{8}x \leq 21\). Start by isolating \(x\) by multiplying both sides by the reciprocal of \(-\frac{7}{8}\), which is \(-\frac{8}{7}\). Multiplying both sides by a negative number will flip the inequality sign, thus:\[ x \geq 21 \times \left(-\frac{8}{7}\right) \]
02
Simplify the Expression
Now, compute the right-hand side:\[ x \geq 21 \times \left(-\frac{8}{7}\right) = 21 \times -\frac{8}{7}\]Simplify:\[ x \geq -24 \]
03
Write the Solution in Interval Notation
The solution \(x \geq -24\) means that \(x\) can be any number greater than or equal to \(-24\). In interval notation, this solution is written as:\[ [-24, \infty) \]
04
Graph the Solution
On a number line, represent this solution by drawing a closed circle at \(-24\) and a line extending to the right towards infinity, indicating all values greater than or equal to \(-24\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Solving Inequalities
Solving inequalities is a fundamental concept in algebra, similar to solving equations, but with a few additional rules. When you are given an inequality like \(-\frac{7}{8}x \leq 21\), the goal is to find all possible values of \(x\) that make the inequality true.
- To solve inequalities, you follow similar steps as you would with equations: isolate the variable on one side.
- However, a critical step in solving inequalities involves remembering that multiplying or dividing both sides of an inequality by a negative number flips the inequality sign.
- This rule is essential because it preserves the truth of the inequality.
Interval Notation
Interval notation is a streamlined way to express the set of solutions for an inequality. It uses parentheses or brackets to show whether endpoints are included or excluded.
- A bracket \([\) or \(]\) denotes that an endpoint is included in the solution set. For example, \([-24, \infty)\) means that -24 is part of the solution set.
- A parenthesis \((\) or \()\) means the endpoint is not included. The infinity symbol always gets a parenthesis, as infinity isn't a number you can reach or include.
Number Line Graphing
Number line graphing is a visual way to represent solutions of inequalities. For students and educators alike, it's a great method to understand and convey the set of possible solution values.
- To graph the solution \(x \geq -24\) on a number line, place a closed circle on -24 to indicate it’s included in the solution set.
- Draw a line extending to the right side of the number line, toward infinity, showing that all numbers greater than -24 are included.
- The rightward direction signifies that the solution set contains all numbers larger than -24, matching the inequality \(x \geq -24\).