Chapter 8: Problem 81
Solve and graph each solution set. $$ -2 \leq \frac{x+2}{-5} \leq 6 $$
Short Answer
Expert verified
-32 \leq x \leq 8
Step by step solution
01
Understand the Problem
The exercise asks to solve and graph the solution set of the compound inequality \[\begin{equation}-2 \leq \frac{x+2}{-5} \leq 6\end{equation}\].
02
Split the Compound Inequality
The inequality \[\begin{equation}-2 \leq \frac{x+2}{-5} \leq 6\end{equation}\] can be split into two inequalities:1. \[\begin{equation}-2 \leq \frac{x+2}{-5}\end{equation}\]2. \[\begin{equation}\frac{x+2}{-5} \leq 6\end{equation}\]
03
Solve the First Inequality
To solve \[\begin{equation}-2 \leq \frac{x+2}{-5}\end{equation}\], we need to multiply both sides by -5. Remember that multiplying by a negative number reverses the inequality sign:\[\begin{equation}-2 \cdot (-5) \- \frac{x+2}{-5} \cdot (-5)\end{equation}\]This simplifies to:\[\begin{equation}10 \geq x+2\end{equation}\]Now, subtract 2 from both sides:\[\begin{equation}10 - 2 \geq x\end{equation}\]Thus, the inequality is:\[\begin{equation}8 \geq x\end{equation}\], or\[\begin{equation}x \leq 8\end{equation}\]
04
Solve the Second Inequality
To solve \[\begin{equation}\frac{x+2}{-5} \leq 6\end{equation}\], we need to multiply both sides by -5. Remember that multiplying by a negative number reverses the inequality sign:\[\begin{equation}\frac{x+2}{-5} \cdot (-5) \geq 6 \cdot (-5)\end{equation}\]This simplifies to:\[\begin{equation}x+2 \geq -30\end{equation}\]Finally, subtract 2 from both sides:\[\begin{equation}x+2 - 2 \geq -30 - 2\end{equation}\]Thus, the inequality is:\[\begin{equation}x \geq -32\end{equation}\]
05
Combine the Solution Sets
Combining \[\begin{equation}x \leq 8\end{equation}\] and \[\begin{equation}x \geq -32\end{equation}\], we get the solution set:\[\begin{equation}-32 \leq x \leq 8\end{equation}\]
06
Graph the Solution Set
To graph the solution set \[\begin{equation}-32 \leq x \leq 8\end{equation}\], draw a number line. Shade the region between -32 and 8, including -32 and 8 because both inequalities have 'less than or equal to' signs.On the number line:1. Draw a closed circle at -32.2. Draw a closed circle at 8.3. Shade the region between -32 and 8.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Solving Inequalities
Solving inequalities involves finding the values of a variable that make the inequality true. For this specific problem, we deal with a compound inequality, where we have two separate inequalities combined with 'and'. The main steps are:
One crucial rule is to reverse the inequality sign when multiplying or dividing by a negative number. For instance, multiplying \(-2 \leq \frac{x+2}{-5}\) by -5 results in \(10 \geq x+2\) which simplifies to \(x \leq 8\). Similarly, solving the second part \(\frac{x+2}{-5} \leq 6\) involves multiplying by -5 to get \(x+2 \geq -30\), resulting in \(x \geq -32\). Combining both solutions, we obtain \(-32 \leq x \leq 8\).
- Split the compound inequality into two simpler inequalities.
- Focus on solving each inequality separately by isolating the variable of interest.
- Combine the obtained solutions.
One crucial rule is to reverse the inequality sign when multiplying or dividing by a negative number. For instance, multiplying \(-2 \leq \frac{x+2}{-5}\) by -5 results in \(10 \geq x+2\) which simplifies to \(x \leq 8\). Similarly, solving the second part \(\frac{x+2}{-5} \leq 6\) involves multiplying by -5 to get \(x+2 \geq -30\), resulting in \(x \geq -32\). Combining both solutions, we obtain \(-32 \leq x \leq 8\).
Graphing Inequalities
Graphing inequalities on a number line visually shows the range of solution sets. This is especially useful for compound inequalities like \(-32 \leq x \leq 8\).
To graph such an inequality:
For instance, the inequality \(-32 \leq x \leq 8\) means any value between -32 and 8, inclusive, satisfies the inequality. Graphing helps visually confirm all possible solutions, making it easier to understand and verify our solution set.
To graph such an inequality:
- Draw a number line and mark the significant points, here -32 and 8.
- Use closed circles on these points since the inequalities include \(\text{≤}\).
- Shade the region between these two points.
For instance, the inequality \(-32 \leq x \leq 8\) means any value between -32 and 8, inclusive, satisfies the inequality. Graphing helps visually confirm all possible solutions, making it easier to understand and verify our solution set.
Number Line
A number line is a straight line with numbers placed at equal intervals or segments along its length. It's a simple yet powerful tool to visually represent numbers, inequalities, and ranges of values.
When graphing solutions of inequalities:
When graphing solutions of inequalities:
- Draw a horizontal line and mark equal intervals.
- Identify and mark points of significance (intersection points).
- Use symbols like closed circles (for \( \leq, \geq \)) or open circles (for \( <, > \)).
- Shade the section of the line that represents all possible solutions.