Chapter 4: Problem 66
Solve each inequality. Graph the solution set and write it using interval notation. $$ \frac{1}{3} x+1<4+5 x $$
Short Answer
Expert verified
Solution: \( x > -\frac{9}{14} \); Interval notation: \((-\frac{9}{14}, \infty)\).
Step by step solution
01
Move Variable Term
Subtract \( \frac{1}{3}x \) from both sides of the inequality to gather like terms on one side. This gives you: \[ 1 < 4 + 5x - \frac{1}{3}x \] Combine the terms on the right: \( 5x - \frac{1}{3}x = \frac{15}{3}x - \frac{1}{3}x = \frac{14}{3}x \). The new inequality is \( 1 < 4 + \frac{14}{3}x \).
02
Isolate the Variable
Subtract 4 from both sides to move the constant to the left side, giving you: \[ 1 - 4 < \frac{14}{3}x \] Simplify the left side to get: \[ -3 < \frac{14}{3}x \]
03
Solve for x
To solve for \( x \), multiply both sides by \( \frac{3}{14} \) (the reciprocal of \( \frac{14}{3} \)) to isolate \( x \): \[ -3 \cdot \frac{3}{14} < x \] Calculating the left side gives: \[ -\frac{9}{14} < x \] This implies that \( x > -\frac{9}{14} \).
04
Write Solution in Interval Notation
The solution in interval notation is written with round brackets since the inequality is strict (not including \( -\frac{9}{14} \)): \( (-\frac{9}{14}, \infty) \).
05
Graph the Solution Set
On a number line, represent the solution set by an open circle at \( -\frac{9}{14} \) and shade all numbers to the right, extending towards positive infinity, indicating all numbers greater than \( -\frac{9}{14} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Inequalities
Graphing inequalities is a way to visually represent the set of possible solutions to an inequality on a number line. When graphing a strict inequality like \( x > -\frac{9}{14} \), follow these steps to create an accurate representation:
- First, locate the number \(-\frac{9}{14}\) on the number line. Since this is not a whole number or a simple fraction, you might approximate its position between \(-1\) and \(0\).
- Use an open circle at \(-\frac{9}{14}\) to show that this point is not included in the solution. An open circle indicates that the endpoint is not part of the solution set.
- Shade or draw a line to the right of this point to indicate that all numbers greater than \(-\frac{9}{14}\) are included in the solution set.
Interval Notation
Interval notation is a concise way of expressing a range of numbers that satisfy an inequality. It uses brackets and parentheses to show whether endpoints are included. Here’s how you can write the solution to the inequality \( x > -\frac{9}{14} \) using interval notation:
- Since the inequality is strict (\( x \) is greater than but not equal to \( -\frac{9}{14} \)), use a parenthesis "(" at \(-\frac{9}{14}\) to indicate that it is not included in the solution set.
- The interval goes to infinity (\( \infty \)), because there is no upper limit to the values \( x \) can take. Remember, infinity is not a number, so it is always represented with a parenthesis.
- Combine these to form the interval: \( (-\frac{9}{14}, \infty) \).
Algebraic Manipulation
Algebraic manipulation is a crucial skill for solving inequalities like \( \frac{1}{3} x + 1 < 4 + 5 x \). It involves rearranging the inequality to isolate the variable and find its potential values. Let's break down the process:
- First, move all terms involving the variable to one side. This involves subtracting \( \frac{1}{3} x \) from both sides so that all terms with \( x \) are together, leaving you with \( 1 < 4 + \frac{14}{3} x \).
- Next, isolate the variable by moving constants to the opposite side. Subtract \(4\) from both sides to simplify, resulting in \(-3 < \frac{14}{3} x \).
- Finally, solve for \( x \). This involves multiplying both sides by the reciprocal of \( \frac{14}{3} \), which is \( \frac{3}{14} \), achieving \( x > -\frac{9}{14} \).