Chapter 1: Problem 92
Solve each inequality analytically. Write the solution set in interval notation. Support the answer graphically. $$\frac{3 x}{2}+\frac{4 x}{7} \geq-5$$
Short Answer
Expert verified
The solution is \( \left[ \frac{-70}{29}, \infty \right) \).
Step by step solution
01
Combine Fractions
First, we need to combine the fractions on the left side of the inequality. The expressions \( \frac{3x}{2} \) and \( \frac{4x}{7} \) have different denominators. To add them, find the least common denominator, which is 14.
02
Rewrite Terms with Common Denominator
Convert each term to a fraction with a common denominator of 14: \( \frac{3x}{2} = \frac{21x}{14} \) and \( \frac{4x}{7} = \frac{8x}{14} \).
03
Add the Fractions
Add the fractions: \( \frac{21x}{14} + \frac{8x}{14} = \frac{29x}{14} \). Now the inequality is \( \frac{29x}{14} \geq -5 \).
04
Eliminate the Fraction
Multiply both sides of the inequality by 14 to eliminate the fraction: \( 29x \geq -70 \).
05
Solve for x
Divide both sides by 29 to solve for \( x \): \( x \geq \frac{-70}{29} \).
06
Write the Solution in Interval Notation
The solution set in interval notation is \( \left[ \frac{-70}{29}, \infty \right) \).
07
Graph the Solution
To graph the solution, draw a number line. Mark the point \( \frac{-70}{29} \), and shade the region to its right, including the point itself, to show all numbers greater than or equal to \( \frac{-70}{29} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fraction Addition
Adding fractions requires a common denominator. This step ensures that you can combine the numerators effectively. In problems like our exercise, where you're adding fractions like \( \frac{3x}{2} \) and \( \frac{4x}{7} \), it's crucial to tackle this first. Here’s how you proceed:
- Determine the least common denominator (LCD) for the fractions. In this case, it's 14 for the denominators 2 and 7.
- Rewrite each fraction with the LCD. Convert \( \frac{3x}{2} \) into \( \frac{21x}{14} \) by multiplying the numerator and denominator by 7. Convert \( \frac{4x}{7} \) into \( \frac{8x}{14} \) by multiplying the numerator and denominator by 2.
- Add the rewritten fractions: \( \frac{21x}{14} + \frac{8x}{14} = \frac{29x}{14} \).
Interval Notation
Interval notation is a neat way to express the range of solutions for inequalities. After solving the inequality, you need to represent the solution in terms of intervals. Here’s what to keep in mind:
- The notation \( \left[ a, b \right) \) indicates all numbers from \( a \) to \( b \), including \( a \) but not \( b \). The square bracket \([\) implies inclusivity, while the parentheses \(()\) mean exclusivity.
- Our exercise resulted in \( x \geq \frac{-70}{29} \). Hence, in interval notation, it becomes \( \left[ \frac{-70}{29}, \infty \right) \).
- Infinity is always paired with a parenthesis \(()\) as it represents an unbounded limit on one side.
Graphical Representation
Visualizing solutions on a number line helps in understanding the span of solutions. In inequalities, it’s crucial to show clearly what values \( x \) can take.
- First, draw a horizontal number line and locate the point \( \frac{-70}{29} \) on it. This value is approximately \(-2.4138\).
- Since our inequality includes \( x \geq \frac{-70}{29} \), use a solid dot at this point to indicate that the point itself is included in the solution set.
- Shade the number line to the right of \( \frac{-70}{29} \) to show all values greater than this point are part of the solution.