Chapter 2: Problem 70
Solve each inequality. Graph the solution set, and write it using interval notation. \(2(3 z-5)+4(z+6) \geq 2(3 z+2)+3 z-15\)
Short Answer
Expert verified
The solution is \(z \geq -25\) and the interval notation is \[[-25, \infty)\].
Step by step solution
01
- Distribute
Apply the distributive property to eliminate the parentheses on both sides of the inequality. Left side: \[2(3z - 5) + 4(z + 6) = 6z - 10 + 4z + 24\] Right side: \[2(3z + 2) + 3z - 15 = 6z + 4 + 3z - 15\]
02
- Combine like terms
Combine the like terms on both sides of the inequality. Left side: \[6z - 10 + 4z + 24 = 10z + 14\] Right side: \[6z + 4 + 3z - 15 = 9z - 11\]
03
- Isolate the variable
Isolate the variable z by first subtracting 9z from both sides of the inequality: \[10z + 14 - 9z \geq 9z - 11 - 9z\] This simplifies the inequality to: \[z + 14 \geq -11\]Next, subtract 14 from both sides: \[z + 14 - 14 \geq -11 - 14\] Simplifying this will give: \[z \geq -25\]
04
- Write the solution in interval notation
The solution set in interval notation is: \[[-25, \infty)\]
05
- Graph the solution set
Graph the solution set on a number line. Shade the region to the right of -25 and include a closed circle at -25 to indicate that -25 is part of the solution.```plaintext<----|====================================> -25 ∞ ```
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Distributive property
The distributive property is a fundamental concept in algebra that allows us to eliminate parentheses by distributing a multiplying factor across the terms inside. In our example, we begin by applying the distributive property to the expression:
- Left side:
\[2(3z - 5) + 4(z + 6) = 6z - 10 + 4z + 24\] - Right side:
\[2(3z + 2) + 3z - 15 = 6z + 4 + 3z - 15\]
Combine like terms
Combining like terms means to add or subtract terms that have the same variable parts. For example, on both sides of our inequality:
- Left side:
\[6z - 10 + 4z + 24 = 10z + 14\] - Right side:
\[6z + 4 + 3z - 15 = 9z - 11\]
Isolate the variable
To find the solution for the variable, we need to isolate it on one side of the inequality. Start by subtracting 9z from both sides:
This simplifies to:
- \[10z + 14 - 9z \geq 9z - 11 - 9z\]
This simplifies to:
- \[z + 14 \geq -11\]
- \[z + 14 - 14 \geq -11 - 14\]
- \[z \geq -25\].
Interval notation
Interval notation is a way of writing subsets of the real number line. It uses parentheses and brackets to describe sets of numbers. In our case, the solution to the inequality is:\[\z \geq -25\].
-
This is written in interval notation as:
\[[-25, \infty)\].
- The bracket [ indicates that -25 is included in the set.
- The parenthesis ) indicates that infinity is not a specific number but rather, it extends indefinitely.
Graphing inequalities
Graphing inequalities helps visualize the range of solutions. On a number line, use a closed circle to indicate a number is included in the solution. Shade the part of the number line that represents all potential values of the variable. For our solution \(z \geq -25\):
The graph shows all values of z that satisfy the inequality, providing a visual way to understand the solution:
``` plaintext<----|====================================>
-25
∞ ``` This representation confirms that any number larger than or equal to -25 satisfies the inequality.
- Place a closed circle at -25.
- Shade the number line to the right of -25 to show all numbers greater than or equal to -25.
The graph shows all values of z that satisfy the inequality, providing a visual way to understand the solution:
``` plaintext<----|====================================>
-25
∞ ``` This representation confirms that any number larger than or equal to -25 satisfies the inequality.