Chapter 1: Problem 21
Solve the linear inequality. Express the solution using interval notation and graph the solution set. $$2 \leq x+5<4$$
Short Answer
Expert verified
The solution in interval notation is \([-3, -1)\).
Step by step solution
01
Understand the Compound Inequality
The given inequality is a compound inequality: \(2 \leq x+5 < 4\). This means we have two separate inequalities to solve: \(2 \leq x+5\) and \(x+5 < 4\). We will solve them individually to find the range of \(x\).
02
Solve the First Inequality
The first inequality is \(2 \leq x+5\). Subtract 5 from both sides to isolate \(x\): \(2 - 5 \leq x\) which simplifies to \(-3 \leq x\).
03
Solve the Second Inequality
The second inequality is \(x+5 < 4\). Subtract 5 from both sides to isolate \(x\): \(x < 4 - 5\). Simplifying this gives \(x < -1\).
04
Combine the Solutions
Now we combine the solutions \(-3 \leq x\) and \(x < -1\). The solution to the compound inequality is \(-3 \leq x < -1\).
05
Express the Solution in Interval Notation
The solution \(-3 \leq x < -1\) can be expressed in interval notation as \([-3, -1)\). This denotes that \(x\) includes \(-3\) but does not include \(-1\).
06
Graph the Solution Set
On a number line, draw a solid dot at \(-3\) to indicate that \(-3\) is included in the solution. Draw an open circle at \(-1\) to show that \(-1\) is not included. Shade the region between \(-3\) and \(-1\) to represent all numbers \(x\) that satisfy the inequality.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Compound Inequality
When faced with a compound inequality, you're dealing with a situation involving two inequalities joined by the words "and" or "or." In the given problem, the expression \(2 \leq x+5 < 4\) is a compound inequality of the form "and." This means we're looking for values of \(x\) that satisfy both inequalities simultaneously.
Here's a quick breakdown:
Here's a quick breakdown:
- The expression \(2 \leq x+5\) requires us to find all values of \(x\) that, when 5 is added, are at least 2.
- The expression \(x+5 < 4\) requires us to find all values of \(x\) that, when 5 is added, are less than 4.
Expressing in Interval Notation
Once you've solved a compound inequality, it's helpful to express the solution in interval notation. This is a concise way to write the range of values that satisfy the inequality.
For our compound inequality solution \(-3 \leq x < -1\), we express it as \([-3, -1)\). The bracket "[" denotes that -3 is included in the solution, while the parenthesis ")" indicates that -1 is not included. Using interval notation can simplify your solution representation and make it more intuitive to interpret and work with.
For our compound inequality solution \(-3 \leq x < -1\), we express it as \([-3, -1)\). The bracket "[" denotes that -3 is included in the solution, while the parenthesis ")" indicates that -1 is not included. Using interval notation can simplify your solution representation and make it more intuitive to interpret and work with.
- A bracket, like \([\) or \(]\), means that the number is part of the solution (inclusive).
- A parenthesis, like \(()\), means that the number is not part of the solution (exclusive).
Graphing Inequalities
Graphing inequalities on a number line helps to visualize the set of possible solutions. For the compound inequality \(-3 \leq x < -1\), you'll see a clear depiction of where \(x\) lies.
Here's how to graph this solution:
Here's how to graph this solution:
- Start by identifying the boundaries: \(-3\) and \(-1\).
- Place a solid dot at \(-3\) to show it's included in the solution. Think of this dot as saying "yes, include -3."
- Place an open circle at \(-1\) to indicate it's not included. An open circle essentially means "just short of -1."
- Shade the number line between \(-3\) and \(-1\). This shaded region represents all the values that \(x\) can be.