Chapter 4: Problem 24
Solve each inequality. Graph the solution set and write it using interval notation. See Example 2. $$ 4 x<-36 $$
Short Answer
Expert verified
The solution in interval notation is \((-\infty, -9)\).
Step by step solution
01
Isolate the Variable
In order to solve the inequality, we want to isolate the variable, which is \(x\). The original inequality is \(4x < -36\). We need to divide both sides of the inequality by \(4\) to isolate \(x\).
02
Divide Both Sides by 4
By dividing both sides of the inequality \(4x < -36\) by \(4\), we get: \[ x < \frac{-36}{4} \] Simplifying the right side gives \(x < -9\).
03
Represent the Solution Set on a Number Line
The solution \(x < -9\) means that \(x\) can be any number less than \(-9\). On a number line, you would indicate this by drawing an open circle at \(-9\) (indicating that \(-9\) is not included in the solution set) and shading the line to the left of \(-9\).
04
Write the Solution in Interval Notation
The interval notation for \(x < -9\) is \((-\infty, -9)\). This notation represents all numbers less than \(-9\).
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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 concise way to represent a range of values that satisfy an inequality. Instead of listing all possible values, interval notation uses certain symbols to define the bounds of the range. Here is how it works:
- Parentheses \((\) or \()\) indicate that a number is not included in the set. For example, in the solution \((-infty, -9)\), this indicates all numbers less than -9, but not including -9 itself.
- Brackets \([\) or \()]\) would be used if the endpoint is included in the solution set, marked as a closed interval.
Graphing Inequalities
Graphing inequalities involves visually representing the range of values that satisfy an inequality on a coordinate plane or number line. To correctly graph an inequality, especially a simple one-variable inequality like \(x < -9\), follow these steps:
- Identify the boundary number: Here, it is -9.
- Decide whether to use an open circle or a closed dot on the number line:
- Use an open circle for inequalities like \(<\) or \(>\), showing the boundary number is not included in the solution.
- Use a closed dot for \(\leq\) or \(\geq\), indicating inclusion.
- Shade the appropriate side of the number line:
- For \(<\), shade to the left.
- For \(>\), shade to the right.
Number Line Representation
A number line is a simple yet powerful tool to visually express inequalities. When representing \(x < -9\) on a number line, here's how you can do it:
Start by drawing a horizontal line and marking even, equally spaced increments. Locate the position of -9 among these increments.
Start by drawing a horizontal line and marking even, equally spaced increments. Locate the position of -9 among these increments.
- Draw an open circle on -9 to indicate that this point is not included in the solution set.
- Shade the line extending from -9 to the left towards negative infinity. This shaded area visually indicates all numbers less than -9 fulfilling the inequality.