Chapter 1: Problem 171
Solve. Graph all solutions on a number line and provide the corresponding interval notation. $$ -4 \leq 3 x+5<11 $$
Short Answer
Expert verified
The solution is \([-3, 2)\) with \(-3\) included and \(2\) not included.
Step by step solution
01
Break Down the Compound Inequality
The compound inequality is given as \[ -4 \leq 3x + 5 < 11. \]This means we have two inequalities to solve: 1. \( -4 \leq 3x + 5 \)2. \( 3x + 5 < 11 \).
02
Solve the First Inequality
Take the first part of the compound inequality:\[ -4 \leq 3x + 5. \]Subtract 5 from both sides:\[ -4 - 5 \leq 3x + 5 - 5 \quad \Rightarrow \quad -9 \leq 3x. \]Divide both sides by 3 to isolate \( x \):\[ \frac{-9}{3} \leq x \quad \Rightarrow \quad -3 \leq x. \]
03
Solve the Second Inequality
Now, solve the second part of the compound inequality:\[ 3x + 5 < 11. \]Subtract 5 from both sides:\[ 3x + 5 - 5 < 11 - 5 \quad \Rightarrow \quad 3x < 6. \]Divide both sides by 3 to find \( x \):\[ x < \frac{6}{3} \quad \Rightarrow \quad x < 2. \]
04
Combine the Solutions
We have two inequalities now:\[ -3 \leq x \quad \text{and} \quad x < 2. \]These can be combined to form the compound inequality:\[ -3 \leq x < 2. \]
05
Graph the Solutions
Graph the solution on a number line. Draw a closed circle at \(-3\) to indicate that \(-3\) is included in the solutions (\(\leq\)), and an open circle at \(2\) to indicate that \(2\) is not included (\(<\)). Shade the entire region between \(-3\) and \(2\) to represent all the values that satisfy the inequality.
06
Write the Interval Notation
The interval notation representing the solution \(-3 \leq x < 2\) is written as:\[ [-3, 2). \]This denotes all numbers from \(-3\) to \(2\), including \(-3\) but not \(2\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Number Line Graph
A number line graph provides a visual representation of inequalities and can help you better understand the range of solutions. In our original problem, we are given the compound inequality \(-3 \leq x < 2\). To correctly graph this on a number line, follow these steps:
- Start by drawing a horizontal line with evenly spaced intervals.
- Mark the points \(-3\) and \(2\) on the line, as these are the boundaries of your solution.
- Since \(-3\) is included in the solution set (indicated by \(\leq\)), represent this with a closed circle on \(-3\).
- Since \(2\) is not included in the solution set (indicated by \(<\)), represent this with an open circle on \(2\).
- Shade the region between the closed circle on \(-3\) and the open circle on \(2\) to demonstrate all the values of \(x\) that satisfy the inequality.
Interval Notation
Interval notation offers a shorthand method for writing a range of numbers defined by inequalities, making it much simpler to understand and use. For the inequality \(-3 \leq x < 2\), the interval notation is written as \([-3, 2)\). Here's why:
- The square bracket \([\) on \(-3\) indicates that \(-3\) is included in the solution (known as a 'closed interval').
- The parenthesis \()\) on \(2\) means \(2\) is not included in the solution (an 'open interval').
- The comma separates the lower and upper bounds of the interval.
Inequality Solutions
Solving inequalities involves finding all possible values of a variable that satisfy the given inequality conditions. For our problem, we started with the compound inequality \(-4 \leq 3x+5 < 11\). This meant finding values of \(x\) that satisfy both parts of this compound inequality:
- The first step was to break the compound inequality into two separate inequalities: \(-4 \leq 3x + 5\) and \(3x + 5 < 11\).
- Each inequality was solved separately, by first isolating \(3x\), then dividing by \(3\) to solve for \(x\).
- For the inequality \(-4 \leq 3x + 5\), we ended up with \(-3 \leq x\).
- For \(3x + 5 < 11\), we found \(x < 2\).
- By combining these, the solution to the original compound inequality was \(-3 \leq x < 2\).