Chapter 8: Problem 37
Solve each compound inequality. Graph the solution set and write it using interval notation. $$ x \leq-2 \text { or } x>6 $$
Short Answer
Expert verified
\((-\infty, -2] \cup (6, \infty)\). Graph includes shaded regions to the left of \(-2\) and to the right of 6.
Step by step solution
01
Understand the Problem
We have a compound inequality given by \( x \leq -2 \text{ or } x > 6 \). This means the solution includes values of \( x \) that satisfy either one or both of these inequalities.
02
Solve Each Inequality Separately
First, solve \( x \leq -2 \). Any number less than or equal to \(-2\) satisfies this inequality. Next, solve \( x > 6 \). Any number greater than 6 satisfies this inequality.
03
Combine the Inequalities
Since the inequalities are joined by 'or', the solution includes all values that meet either \( x \leq -2 \) or \( x > 6 \).
04
Graph the Solution Set
On a number line, shade the region from negative infinity to -2 and include -2 (use a closed dot for \(-2\)), and then shade the region greater than 6 with an open dot (not including 6).
05
Write in Interval Notation
The interval for the solution set combines both parts: \( (-\infty, -2] \cup (6, \infty) \). '(-∞, -2]' indicates all numbers less than or equal to \(-2\) and '(6, ∞)' includes all numbers greater than 6.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Inequality Solving
Inequality solving involves finding all values of a variable that make an inequality true. In the given exercise, we work with a *compound inequality* that includes the word 'or'. It looks like this: \( x \leq -2 \text{ or } x > 6 \). This means we're looking for numbers that satisfy one inequality, the other, or both.
To solve the inequalities separately:
To solve the inequalities separately:
- For \( x \leq -2 \): Solve by determining all values that are less than or equal to -2. Remember, 'less than or equal to' is often shown on a graph with a closed dot.
- For \( x > 6 \): Solve by finding values greater than 6. Here, 'greater than' is represented with an open dot on a graph. Open dots indicate the number itself is not a part of the solution.
Interval Notation
Interval notation is a way of expressing the set of solutions for an inequality. It’s compact and includes specific symbols to show which numbers are included in a set. Let’s explore this further using our solved inequalities:
- For \( x \leq -2 \), in interval notation, this is \((-\infty, -2]\). The parenthesis \((-\infty\) indicates that infinity is not a number, thus never included, and the bracket \(-2]\) signifies that -2 is included.
- For \( x > 6 \), it becomes \((6, \infty)\). Here, the parenthesis on both sides denotes that 6 is not included, and infinity naturally isn't a part of any set.
Graphing Inequalities
Graphing inequalities on a number line gives a clear visual representation of the solution set. Let’s recap our example:
- To graph \( x \leq -2 \): On a number line, shade the area to the left of -2. Use a closed dot at -2 to show it is included in the solution.
- To graph \( x > 6 \): Shade the area to the right of 6 with an open dot at 6, indicating that while numbers greater than 6 are part of the solution, 6 itself is not included.