Chapter 2: Problem 102
Solve each equation and inequality. Write the solution set of each inequality in interval notation and graph it. $$ \text { a. }-16<4(x+8) \leq 8 \quad \text { b. }-16=4(x+8)+8 $$
Short Answer
Expert verified
a. Interval:
\((-12, -6]\)
Equation:
\(x = -14\)
Step by step solution
01
Simplify each side of the inequality
For the inequality \[-16<4(x+8) \leq 8\]First, distribute the 4 to both terms inside the parentheses:\[-16 < 4x + 32 \leq 8\]
02
Solve the inequality
Subtract 32 from all parts of the inequality to isolate the term containing x:\[-16 - 32 < 4x \leq 8 - 32\]This simplifies to:\[-48 < 4x \leq -24\]Now, divide all parts by 4 to solve for x:\[-12 < x \leq -6\]
03
Write the solution set in interval notation
The solution set for the inequality is \(-12 < x \leq -6\),which in interval notation is:\((-12, -6]\)
04
Graph the solution set on a number line
Draw a number line. Open circle on -12 (not included), closed circle on -6 (included), and shade between them to represent the interval:\( ext{------(====âš«]}\)where ... represents values less than -12, and === represents values between -12 and -6 inclusive.
05
Simplify the equation
For the equation \[-16=4(x+8)+8\]Distribute the 4 inside the parentheses:\[-16 = 4x + 32 + 8\]Combine like terms:\[-16 = 4x + 40\]
06
Isolate the variable
To solve for x, first subtract 40 from both sides of the equation:\[-16 - 40 = 4x\]This simplifies to:\[-56 = 4x\]Now, divide both sides by 4:\[-14 = x\]
07
Solution for the equation
The solution of the equation is \(x = -14\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Interval Notation
Interval notation is a mathematical way of expressing a range of values. It's often used to convey solutions to inequalities in a compact form. When using interval notation, you denote the beginning and end of an interval, indicating which values are included or excluded.
Here's how it works:
Here's how it works:
- Round brackets, \( ( \) and \ ) \, are used for values that are not included in the interval (open interval).
- Square brackets, \[ [ \] \ and \ ] \, are used for values that are included in the interval (closed interval).
- The interval \((-12, -6]\) means -12 is not included in the solution set, while -6 is included.
Number Line Graph
A number line graph is a visual representation of numbers on a straight line. This helps in clearly showing the solution set for an inequality. When graphing intervals:
- An open circle represents a number not included in the interval (e.g., -12 in \((-12, -6]\)).
- A closed circle represents a number that is included in the interval (e.g., -6 in \((-12, -6]\)).
- A shaded region between the circles indicates all the numbers that are part of the solution set.
Distributive Property
The distributive property is a foundational principle used in algebra to multiply a single term across terms within parentheses. For example, when you see an expression like \(4(x+8)\), you distribute the 4 across both \(x\) and 8.
- To apply the distributive property, multiply the term outside the parentheses by each term inside the parentheses: \(4(x+8) = 4x + 32\).
- This property helps simplify expressions and equations, making them easier to solve.
- By distributing before isolating variables, it ensures all components are accounted for in the simplification process.