Chapter 2: Problem 73
Solve and graph the solution set. In addition, present the solution set in interval notation. $$ 3 x \leq-15 \text { or } 2 x>6 $$
Short Answer
Expert verified
Solution set: \((-\infty, -5] \cup (3, \infty)\).
Step by step solution
01
Solve the first inequality
Start by solving the inequality \(3x \leq -15\). Divide both sides of the inequality by 3 to isolate \(x\). The solution becomes \(x \leq -5\).
02
Solve the second inequality
Now, solve the inequality \(2x > 6\). Divide both sides by 2 to isolate \(x\). The solution becomes \(x > 3\).
03
Combine the solutions and express in interval notation
Since we have an 'or' condition, combine the solutions \(x \leq -5\) or \(x > 3\). In interval notation, this is expressed as \((-\infty, -5] \cup (3, \infty)\).
04
Graph the solution set
To graph the solution set on a number line, draw a closed circle at \(-5\) to represent \(x \leq -5\), and shade all numbers to the left. Draw an open circle at 3 and shade to the right to represent \(x > 3\). The shaded parts on both ends of the number line indicate the combined solutions for the inequality.
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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 convenient way of expressing the solution set of an inequality. It provides a clear and concise representation of ranges of numbers. When using interval notation:
- Parentheses \((...,... )\) are used to indicate that an endpoint is not included in the interval. This is known as an open interval.
- Brackets \([..., ... ]\) indicate that an endpoint is included. This is called a closed interval.
Number Line Graph
A number line graph visually represents the solution set of an inequality. It helps to understand the range of values that satisfy the inequality. When graphing the solution set:
- An open circle at a point like 3 indicates that this value is not included in the solution set, as in the inequality \(x > 3\).
- A closed circle indicates inclusion, as in \(x \leq -5\), where a closed circle is placed at -5.
Compound Inequality
A compound inequality involves two distinct inequalities joined by "and" or "or." It defines a condition where at least one or both parts of the inequality must be true.
- If connected with "and," both conditions must be satisfied simultaneously.
- If connected with "or," satisfying either inequality makes the entire statement true. This is the case in the example \(3x \leq -15 \text{ or } 2x > 6\).
Solution Set Representation
Representing a solution set effectively communicates the solution to inequalities. It can be expressed in multiple formats such as algebraic expressions, interval notation, or graphically on a number line. For our example:
- Algebraically, it's shown as \(x \leq -5\) or \(x > 3\).
- Interval notation presents it as \((-\infty, -5] \cup (3,\infty)\).
- The number line graph visualizes it with shaded areas and open/closed circles.