Chapter 2: Problem 100
Solve each equation and inequality. Write the solution set of each inequality in interval notation and graph it. a. \(7(a-3)<2(5 a-8)\) b. \(7(a-3)=2(5 a-8)\)
Short Answer
Expert verified
a. The solution in interval notation is \((-\frac{5}{3}, \infty)\).
b. The solution is \(a = -\frac{5}{3}\).
Step by step solution
01
Distribute and Simplify Both Sides of the Inequality
For inequality \(7(a-3)<2(5a-8)\), start by applying the distributive property to both sides.\[ 7a - 21 < 10a - 16 \]
02
Reorganize to Isolate Variable 'a' on One Side
Subtract \(7a\) from both sides to move all terms involving 'a' to one side:\[ -21 < 3a - 16 \]
03
Obtain the Inequality For 'a'
Add 16 to both sides to isolate terms with 'a' completely on the right side:\[ -5 < 3a \]Divide both sides by 3:\[ a > -\frac{5}{3} \]
04
Express the Solution in Interval Notation and Graph It
The solution for the inequality is \(a > -\frac{5}{3}\). In interval notation, this is written as:\((-\frac{5}{3}, \infty)\)Graphically, this is represented as an open interval starting just after \(-\frac{5}{3}\) extending to the right indefinitely.
05
Apply Distributive Property to the Equation
For the equation \(7(a-3)=2(5a-8)\), distribute each side:\[ 7a - 21 = 10a - 16 \]
06
Rearrange to Isolate 'a' in the Equation
Subtract \(7a\) from both sides to gather 'a' terms:\[ -21 = 3a - 16 \]
07
Solve for 'a' in the Equation
Add 16 to each side:\[ -5 = 3a \]Now, divide both sides by 3:\[ a = -\frac{5}{3} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Distributive Property
The distributive property is a fundamental concept in algebra that allows us to multiply a single term by two or more terms inside a parenthesis. This property is particularly useful when solving equations and inequalities.
When you see an expression like \(7(a-3)\), the distributive property lets you expand it into \(7 \cdot a - 7 \cdot 3\), which simplifies to \(7a - 21\). In the same way, for \(2(5a-8)\), you would end up with \(2 \cdot 5a - 2 \cdot 8\), simplifying to \(10a - 16\).
Key points about the distributive property include:
When you see an expression like \(7(a-3)\), the distributive property lets you expand it into \(7 \cdot a - 7 \cdot 3\), which simplifies to \(7a - 21\). In the same way, for \(2(5a-8)\), you would end up with \(2 \cdot 5a - 2 \cdot 8\), simplifying to \(10a - 16\).
Key points about the distributive property include:
- It works for both addition and subtraction inside the parenthesis.
- It's often the first step in simplifying expressions and solving equations.
- Applying it correctly helps to eliminate parentheses in an equation or inequality.
The Role of Interval Notation
Interval notation is a concise way to express a range of numbers, often used with inequalities. It shows us which values are solutions for a given inequality. For example, if you see \(a > -\frac{5}{3}\), it means all values greater than \(-\frac{5}{3}\) satisfy the inequality.
We write this as \((-\frac{5}{3}, \infty)\), meaning all numbers between \(-\frac{5}{3}\) and infinity, but not including \(-\frac{5}{3}\) itself. The round parenthesis \(()\) indicates that \(-\frac{5}{3}\) is not part of the solution set whereas a square bracket \([]\) would indicate inclusion.
Things to remember about interval notation:
We write this as \((-\frac{5}{3}, \infty)\), meaning all numbers between \(-\frac{5}{3}\) and infinity, but not including \(-\frac{5}{3}\) itself. The round parenthesis \(()\) indicates that \(-\frac{5}{3}\) is not part of the solution set whereas a square bracket \([]\) would indicate inclusion.
Things to remember about interval notation:
- Round brackets \(()\) are used for numbers not included in the interval.
- Square brackets \([]\) indicate numbers that are included.
- When the interval extends to infinity, always use a round bracket since infinity is not a number you can reach or include.
Graphical Representation of Solutions
Graphical representation is a visual method for displaying interval solutions on the number line. It helps you see the range of possible solutions for equations and inequalities.
For the inequality \(a > -\frac{5}{3}\), a graph would show an open circle at \(-\frac{5}{3}\) on the number line, extending indefinitely to the right. The open circle indicates that the value \(-\frac{5}{3}\) is not included in the solution.
Important aspects of graphical representation include:
For the inequality \(a > -\frac{5}{3}\), a graph would show an open circle at \(-\frac{5}{3}\) on the number line, extending indefinitely to the right. The open circle indicates that the value \(-\frac{5}{3}\) is not included in the solution.
Important aspects of graphical representation include:
- An open circle shows a number not included in the interval, while a closed dot shows inclusion.
- An arrow indicates that the solutions continue indefinitely in that direction.
- Graphical representation makes it easier to understand the breadth and limits of a solution set visually.