Chapter 2: Problem 111
Solve. Graph the solutions on a number line and give the corresponding interval notation. $$|2 x+3|<1$$
Short Answer
Expert verified
The solution is \(-2 < x < -1\), or \((-2, -1)\) in interval notation.
Step by step solution
01
Understand the Absolute Value Inequality
The inequality \(|2x+3| < 1\) means that the expression inside the absolute value, \(2x+3\), is between -1 and 1. Therefore, we can write two separate inequalities: \(-1 < 2x + 3 < 1\).
02
Solve the Left Part of the Inequality
First, solve \(-1 < 2x + 3\). Subtract 3 from both sides to get \(-4 < 2x\). Then divide by 2 to obtain \(-2 < x\).
03
Solve the Right Part of the Inequality
Next, solve \(2x + 3 < 1\). Subtract 3 from both sides to get \(2x < -2\). Then divide by 2 to obtain \(x < -1\).
04
Combine the Inequalities
Combine the results from the two inequalities to get the solution: \(-2 < x < -1\). This is the range of values for \(x\) that satisfy the original inequality.
05
Graph the Solution on a Number Line
Draw a number line and shade the region between \(x = -2\) and \(x = -1\). Use open circles at -2 and -1 to indicate that these endpoints are not included in the solution set.
06
Write the Interval Notation
The solution, \(-2 < x < -1\), can be written in interval notation as \((-2, -1)\). This notation indicates the continuous range of x-values between -2 and -1, excluding -2 and -1 themselves.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
number line graphing
Graphing on a number line is a visual way to represent inequalities. It helps in understanding which values are included in the solution set. For the inequality \(-2 < x < -1\), we only include values between -2 and -1. This interval is shown with open circles on the number line, indicating that -2 and -1 are not part of the solution.
To graph it:
To graph it:
- Draw a straight line and label a section of it with numbers, say from -3 to 0.
- Locate -2 and -1 on this line.
- Place open circles at -2 and -1 because these numbers are not included in the solution set (use of open circles for values not included is important).
- Shade the space between these open circles to show all the possible values of \(x\).
interval notation
Interval notation is a concise way to express the range of solutions in inequalities. For our solution \(-2 < x < -1\), interval notation captures this as \((-2, -1)\). The parentheses \(()\) indicate that -2 and -1 are not part of the solution, aligning with the open circles on the number line graph.
Here's how interval notation works:
Here's how interval notation works:
- Parentheses \(()\) are used for numbers not included in the solution set.
- Brackets \([]\) mean the number is included in the set.
- The format is always \((\text{lower bound}, \text{upper bound})\) or \([\text{lower bound}, \text{upper bound}]\).
solving compound inequalities
Compound inequalities involve two simple inequalities combined. The solution must satisfy both to be true. After breaking down the absolute value inequality \(|2x+3| < 1\), we split it into two: \(-1 < 2x+3 < 1\). This creates a compound inequality requiring careful solving.
Steps:
Steps:
- Write the compound inequality, like \(-1 < 2x+3 < 1\).
- Solve the left side: subtract 3 from \(-1\) giving \(-4 < 2x\), then divide by 2 to find \(x > -2\).
- Solve the right side: subtract 3 from \(1\) to get \(2x < -2\), then divide by 2 to find \(x < -1\).
- Combine both to yield \(-2 < x < -1\), meaning both conditions must be met simultaneously.