Chapter 17: Problem 21
Solve the given inequalities. Graph each solution. It is suggested that you also graph the function on a calculator as a check. $$\frac{x}{x+3} > 1$$
Short Answer
Expert verified
The solution is \( x < -3 \). On a number line, shade left of \(-3\) with an open circle at \(-3\).
Step by step solution
01
Set Up the Inequality
The given inequality is \( \frac{x}{x+3} > 1 \). To solve this, we first move everything to one side to set the inequality to zero by subtracting 1 from both sides.
02
Simplify the Inequality
Subtract 1 from both sides to obtain \( \frac{x}{x+3} - 1 > 0 \). Simplifying this further, we get \( \frac{x - (x+3)}{x+3} > 0 \).
03
Simplify the Numerator
Combine the terms in the numerator: \( x - (x+3) = x - x - 3 = -3 \). The inequality becomes \( \frac{-3}{x+3} > 0 \).
04
Analyze the Fraction
For a fraction \( \frac{-3}{x+3} > 0 \) to be positive, the denominator \( x+3 \) must be negative since the numerator \(-3\) is negative.
05
Solve for the Variable
Solve for \( x \) in \( x+3 < 0 \). Subtracting 3 from both sides gives \( x < -3 \).
06
Graph the Solution
On the number line, shade to the left of \( -3 \) to represent all numbers less than \( -3 \). Since \( x eq -3 \), use an open circle at \( x = -3 \).
07
Verify on a Graphing Calculator
Graph the function \( y = \frac{x}{x+3} \) and the line \( y = 1 \) on a calculator. Check the graph to ensure the section where the function is above the line occurs when \( x < -3 \).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Solutions
Graphing solutions of inequalities is a visual way to understand the solution set. It helps to see which x-values satisfy the inequality. In our exercise, we solved the inequality \( \frac{x}{x+3} > 1 \). This means finding the x-values for which the expression is greater than 1.
Once we simplified the inequality to \( \frac{-3}{x+3} > 0 \), we need to look at the graph. Plot the expression on a number line. The expression equals zero or undefined at the point where the denominator is zero, which happens at \( x = -3 \). Therefore, our number line should be centered around this point.
Shade on the left side of \( x = -3 \). This is because our analysis shows that the expression becomes positive when \( x < -3 \). Make sure to indicate an open circle at \( x = -3 \) to show it is not included in the solution set. This graphical representation not only makes inequalities visually distinct but also aids in verifying your solutions.Using a graphing calculator can further reinforce this by allowing you to compare the expression graph of \( y = \frac{x}{x+3} \) with the line \( y = 1 \). Where \( \frac{x}{x+3} \) is above \( y = 1 \), you visually confirm the inequality holds.
Once we simplified the inequality to \( \frac{-3}{x+3} > 0 \), we need to look at the graph. Plot the expression on a number line. The expression equals zero or undefined at the point where the denominator is zero, which happens at \( x = -3 \). Therefore, our number line should be centered around this point.
Shade on the left side of \( x = -3 \). This is because our analysis shows that the expression becomes positive when \( x < -3 \). Make sure to indicate an open circle at \( x = -3 \) to show it is not included in the solution set. This graphical representation not only makes inequalities visually distinct but also aids in verifying your solutions.Using a graphing calculator can further reinforce this by allowing you to compare the expression graph of \( y = \frac{x}{x+3} \) with the line \( y = 1 \). Where \( \frac{x}{x+3} \) is above \( y = 1 \), you visually confirm the inequality holds.
Inequality Simplification
Inequality simplification involves manipulating an inequality into a form that's easier to solve. In our example, the inequality \( \frac{x}{x+3} > 1 \) involved dividing each side to simplify. The goal here is to get zero on one side so you can focus on just the inequality expression itself.
By subtracting 1 from both sides, you create a new expression: \( \frac{x}{x+3} - 1 > 0 \). Simplifiers love this method because simplifying is often about making things as neat as possible. You can rewrite the term to \( \frac{x - (x+3)}{x+3} > 0 \), thereby revealing the true nature of the fraction.
Remember, simplification is a crucial step. It lets us see that the equation expresses something like \( \frac{-3}{x+3} > 0 \). This clean form helps in the next stage of simply analyzing signs of the terms to solve the inequality.
By subtracting 1 from both sides, you create a new expression: \( \frac{x}{x+3} - 1 > 0 \). Simplifiers love this method because simplifying is often about making things as neat as possible. You can rewrite the term to \( \frac{x - (x+3)}{x+3} > 0 \), thereby revealing the true nature of the fraction.
Remember, simplification is a crucial step. It lets us see that the equation expresses something like \( \frac{-3}{x+3} > 0 \). This clean form helps in the next stage of simply analyzing signs of the terms to solve the inequality.
Numerator and Denominator Analysis
Analyzing the numerator and denominator of a fraction is key to understanding when the fraction itself is positive or negative. This analysis helps us determine where the inequality \( \frac{-3}{x+3} > 0 \) holds true.
Here's the trick: realize the numerator is \(-3\)—always negative. For the fraction to be positive, the denominator \( x+3 \) must also be negative. That happens when \( x < -3 \).
From this perspective, analysis simplifies down to two parts:
Here's the trick: realize the numerator is \(-3\)—always negative. For the fraction to be positive, the denominator \( x+3 \) must also be negative. That happens when \( x < -3 \).
From this perspective, analysis simplifies down to two parts:
- Determine the sign of the numerator.
- Set up the inequality for the denominator to match the necessary sign for the solution.