Chapter 0: Problem 17
Find the solution set, graph this set on the real line, and express this set in interval notation. $$ \frac{3}{1-x} \leq 2 $$
Short Answer
Expert verified
The solution set is \((-\infty, -\frac{1}{2}]\).
Step by step solution
01
Set Up the Inequality
We start with the given inequality \( \frac{3}{1-x} \leq 2 \). Our goal is to solve for \( x \). To do this, we need to clear the fraction first.
02
Clear the Fraction
Multiply both sides of the inequality by \( 1-x \) to eliminate the fraction. However, since \( 1-x \) may be negative, we must account for this when multiplying. Let's first consider when \( 1-x > 0 \), which implies \( x < 1 \): \( 3 \leq 2(1-x) \).
03
Solve the Inequality for x < 1
Distribute the right-hand side: \( 3 \leq 2 - 2x \).Now solve for \( x \) by subtracting 2 from both sides: \( 1 \leq -2x \).Divide by \( -2 \) and remember to flip the inequality sign: \( x \leq -\frac{1}{2} \).
04
Consider the Case When x = 1
If \( x = 1 \), then the expression \( \frac{3}{1-x} \) becomes undefined, which means \( x = 1 \) cannot be part of the solution set.
05
Write the Solution Set
Combining results, the solution set for the inequality is \( x \leq -\frac{1}{2} \). The restriction \( x < 1 \) doesn't change the solution since \( x \leq -\frac{1}{2} \) is already smaller than 1.
06
Express in Interval Notation
Expressing the solution \( x \leq -\frac{1}{2} \) in interval notation gives \( (-\infty, -\frac{1}{2}] \).
07
Graph the Solution on the Real Line
On a number line, shade all values to the left of \(-\frac{1}{2}\) and include \(-\frac{1}{2}\) with a filled dot, indicating that it is part of the solution set.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fractions
When solving inequalities involving fractions, such as \( \frac{3}{1-x} \leq 2 \), the primary goal is to clear the fraction to simplify the equation. This is achieved by eliminating the denominator through multiplication. However, caution is warranted because multiplication or division by a negative number necessitates flipping the inequality sign.
- Identify the denominator: In \( \frac{3}{1-x} \), 1-x is the denominator.
- Clear the fraction: Multiply through by \( 1-x \), ensuring to consider the sign of this term as it affects the inequality.
- Handle cases: Determine if \( 1-x \) is positive or negative by solving \( 1-x=0 \) to find boundary conditions.
Interval Notation
Interval notation offers a streamlined method to express solution sets of inequalities. This approach captures the set of all numbers satisfying the inequality in a concise manner. Consider the inequality result \( x \leq -\frac{1}{2} \).
- Use interval brackets: Square brackets \([ \text{ ]} \) are used when the number is included (\( \leq, \geq \)), whereas parentheses \(( \text{ )} \) signify exclusion.
- Identify extremes: For \( x \leq -\frac{1}{2} \), the solution is all numbers from negative infinity up to and including \(-\frac{1}{2} \).
- Express the range: This is written as \( (-\infty, -\frac{1}{2}] \).
Real Number Line
Graphing on the real number line helps visualize solution sets in a clear manner. The real number line extends infinitely in both directions, going left for negative numbers and right for positive numbers. Visualizing the solution, \( x \leq -\frac{1}{2} \), involves a straightforward shading process.
- Identify the boundary: Locate \(-\frac{1}{2} \) on the number line.
- Shade the solution set: Shade all numbers to the left of \(-\frac{1}{2} \), representing numbers \( x \leq -\frac{1}{2} \), while using a filled dot at \(-\frac{1}{2} \) to denote inclusion in the set.
- Understand infinite continuation: The shading extends to the left indefinitely, in line with \( (-\infty, -\frac{1}{2}] \).