Chapter 2: Problem 56
For Problems 45-56, solve each compound inequality using the compact form. Express the solution sets in interval notation. $$ -4<3-x<4 $$
Short Answer
Expert verified
The solution is \((-1, 7)\).
Step by step solution
01
Break Down the Compound Inequality
The compound inequality \(-4 < 3 - x < 4\) can be split into two separate inequalities: 1. \(-4 < 3 - x\) 2. \(3 - x < 4\). We'll solve each inequality step by step.
02
Solve the First Inequality
Start with the inequality \(-4 < 3 - x\). First, subtract 3 from both sides: \(-4 - 3 < -x\) which simplifies to:\(-7 < -x\). Next, multiply each side by -1 to solve for \(x\), remembering to reverse the inequality sign:\(7 > x\) or equivalently, \(x < 7\).
03
Solve the Second Inequality
Now solve the inequality \(3 - x < 4\). Subtract 3 from both sides:\(-x < 1\).Multiply each side by -1 and reverse the inequality:\(x > -1\).
04
Combine the Solutions
With \(x > -1\) from Step 3 and \(x < 7\) from Step 2, you can combine these two results to form the solution of the compound inequality.This gives:\(-1 < x < 7\).
05
Express the Solution in Interval Notation
Translate the compound inequality \(-1 < x < 7\) into interval notation. The interval notation is: \((-1, 7)\). This represents all numbers between -1 and 7, not including the endpoints.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Interval Notation
Interval notation is a way of expressing subsets of real numbers on the number line. It provides a concise way to describe the range of solutions for inequalities. By using brackets and parentheses, we indicate whether endpoints are included or excluded from the solution set. For example, if a solution includes all numbers between -1 and 7, excluding -1 and 7 themselves, it's written as \((-1, 7)\).
- Parentheses \(()\) are used when the endpoints are not included, meaning the values are "open."
- Brackets \([]\) are used to include the endpoints, indicating "closed" values.
Solving Inequalities
Solving inequalities is similar to solving equations, with a few additional steps. To find the solution for an inequality like \(3 - x < 4\), we perform operations common to solving equations:
For example:
- Adding or subtracting numbers from both sides.
- Multiplying or dividing both sides by a positive number.
For example:
- If you have \(-x < 1\), multiplying by -1 to make \(x\) positive requires flipping the < symbol to >, resulting in \(x > -1\).
Reversing Inequality Signs
Reversing inequality signs is a vital concept in solving inequalities. This normally occurs when you multiply or divide each side of an inequality by a negative number. It ensures the inequality relation remains accurate. For example, when dealing with \(-x < 1\), multiplying both sides by -1 yields \(x > -1\). The inequality sign is reversed from < to > during this operation.
- Make sure to reverse the inequality sign any time you multiply or divide by a negative value.
- Remember that this step is crucial to keeping the inequality true.