Chapter 1: Problem 11
Solve the linear inequality. Express the solution using interval notation and graph the solution set. $$2 x+1<0$$
Short Answer
Expert verified
The solution is \((-\infty, -\frac{1}{2})\).
Step by step solution
01
Isolate the variable term
Start by isolating the term containing the variable. We have the inequality \(2x + 1 < 0\). To isolate \(2x\), subtract 1 from both sides of the inequality:\[2x + 1 - 1 < 0 - 1\]which simplifies to:\[2x < -1\]
02
Solve for the variable
Next, solve for \(x\) by dividing both sides of the inequality by 2. Remember to divide the entire inequality by 2:\[\frac{2x}{2} < \frac{-1}{2}\]This simplifies to:\[x < -\frac{1}{2}\]
03
Express the solution in interval notation
The solution \(x < -\frac{1}{2}\) means that \(x\) can be any number less than \(-\frac{1}{2}\). In interval notation, this is written as:\((-\infty, -\frac{1}{2})\)
04
Graph the solution set
To graph the solution set on a number line, draw an open circle at \(-\frac{1}{2}\) to indicate that \(-\frac{1}{2}\) is not included in the solution set. Then shade the region to the left of \(-\frac{1}{2}\) to show that all numbers less than \(-\frac{1}{2}\) are included.
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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 way of writing subsets of the real number line. It provides a concise way to convey the range of numbers that satisfy a particular condition.
For understanding interval notation, always remember:
Therefore, the interval notation for the solution is \((-\infty, -\frac{1}{2})\). Trust that this simple notation will help accurately convey complex sets of numbers.
For understanding interval notation, always remember:
- Parentheses \( ( \, \ ) \) are used when an endpoint is not included in the set, indicating an open interval.
- Brackets \( [ \, \ ] \) are used when an endpoint is included, indicating a closed interval.
- Infinity \( \infty \) is always paired with a parenthesis because it is not a number that can be "reached," implying openness.
Therefore, the interval notation for the solution is \((-\infty, -\frac{1}{2})\). Trust that this simple notation will help accurately convey complex sets of numbers.
Solution Set
A solution set is a collection of all solutions of a given inequality or equation. For the inequality \(2x + 1 < 0\), we found the solution to be \(x < -\frac{1}{2}\). This simplifies to creating a set of numbers that are all less than \(-\frac{1}{2}\), and it's vital to understand that each element in this set satisfies the inequality when substituted back into the original equation.
Imagine testing number values in this set:
Imagine testing number values in this set:
- Numbers like \(-1\), \(-2\), or even \(-10\) all work because they are less than \(-\frac{1}{2}\).
- However, numbers like \(-\frac{1}{4}\) or \(0\) do not, as they exceed \(-\frac{1}{2}\).
Number Line Graph
The number line graph is a visual representation of the solution set. It's a simple yet powerful tool to understand and express inequalities. For our inequality \(x < -\frac{1}{2}\), we need a number line to illustrate this.
Here's how you can graphically represent this interval:
Here's how you can graphically represent this interval:
- Start by drawing a straight horizontal line — this is your number line.
- Locate and mark the point \(-\frac{1}{2}\) on the line.
- Since \(-\frac{1}{2}\) is not included, we use an "open circle," signaling it's not part of the solution set.
- Shade the line to the left of this open circle to indicate that numbers less than \(-\frac{1}{2}\) are solutions.