Chapter 4: Problem 60
Solve each inequality. Graph the solution set and write it using interval notation. $$ 5(3+z)>-3(z+3) $$
Short Answer
Expert verified
The solution is \( (-3, +\infty) \).
Step by step solution
01
Expand Both Sides
Start by expanding both sides of the inequality. Distribute the 5 on the left-hand side and the -3 on the right-hand side:On the left: \[ 5(3 + z) = 15 + 5z \]On the right:\[ -3(z + 3) = -3z - 9 \]
02
Combine the Inequality
Substitute the expanded terms back into the inequality:\[ 15 + 5z > -3z - 9 \]
03
Move Variable Terms to One Side
Add \(3z\) to both sides to get all variable terms on one side:\[ 15 + 5z + 3z > -9 \]This simplifies to:\[ 15 + 8z > -9 \]
04
Isolate the Variable Term
Subtract 15 from both sides to isolate the term with \(z\):\[ 8z > -9 - 15 \]This simplifies to:\[ 8z > -24 \]
05
Solve for \(z\)
Divide both sides by 8 to solve for \(z\):\[ z > \frac{-24}{8} \]Which simplifies to:\[ z > -3 \]
06
Write the Solution in Interval Notation
The solution set for \(z > -3\) in interval notation is:\((-3, +\infty)\)
07
Graph the Solution Set
On a number line, draw an open circle at \(-3\) and shade the line extending to the right, indicating all values greater than \(-3\).
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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 method used to describe a set of numbers or a solution set for inequalities in a compact and precise way. In our example, we arrived at the solution for the inequality as \(z > -3\). This means that \(z\) can take any value greater than \(-3\). We express this with interval notation as \((-3, \infty)\).
- The parentheses \(()\) are used because \(-3\) is not included in the solution—it's an open boundary.
- The infinity symbol \(\infty\) always has a parenthesis because infinity isn't a specific number we can reach.
Graphing Inequalities
Graphing inequalities involves representing the solution set of an inequality visually on a number line. For \(z > -3\), we want to show all possible values greater than \(-3\).
- First, identify the number that your variable is greater than—in this case, \(-3\).
- Place an open circle on the number line at \(-3\) to indicate that \(-3\) itself is not included.
- Shade the region to the right of the \(-3\) to show where all numbers greater than \(-3\) lie.
Solving Linear Inequalities
Solving linear inequalities involves similar steps to solving equations, with a few additional considerations. For example, when we solved the inequality \(5(3+z)>-3(z+3)\), we used several steps:
- Expand each side: Distribute the numbers outside the parentheses to get rid of them so you have a clear algebraic expression to work with.
- Combine like terms: Rearrange the inequality to have all terms with the variable on one side.
- Isolate the variable: Move constants to the other side to make one side only about the variable.
- Solving: Divide or multiply to solve for the variable, remembering if you multiply or divide by a negative number, flip the inequality sign.