Chapter 2: Problem 46
Find the equation of the line: Parallel to \(8 x-3 y=24\) and passing through \((-9,4)\).
Short Answer
Expert verified
The equation of the line is \(y = \frac{8}{3}x + 28\).
Step by step solution
01
Identify the Slope of the Given Line
The given line is expressed in standard form as \(8x - 3y = 24\). To find its slope, we first convert it into slope-intercept form, \(y = mx + b\), where \(m\) is the slope. Rearrange the equation to solve for \(y\):\[8x - 3y = 24 \Rightarrow -3y = -8x + 24 \Rightarrow y = \frac{8}{3}x - 8\]The slope \(m\) of the given line is \(\frac{8}{3}\).
02
Determine the Slope of the Parallel Line
Since parallel lines have the same slope, the slope of the line we need to find is also \(\frac{8}{3}\).
03
Use the Point-Slope Form to Write the Equation
The point-slope form of a line is \(y - y_1 = m(x - x_1)\), where \((x_1, y_1)\) is a given point on the line and \(m\) is the slope. Substituting \((-9, 4)\) for \((x_1, y_1)\) and \(\frac{8}{3}\) for \(m\):\[y - 4 = \frac{8}{3}(x + 9)\]
04
Simplify to Obtain the Slope-Intercept Form
Expand and simplify the equation from Step 3 to the slope-intercept form \(y = mx + b\):\[y - 4 = \frac{8}{3}x + \frac{8}{3} \cdot 9\]Calculate \(\frac{8}{3} \cdot 9 = 24\), so the equation becomes:\[y - 4 = \frac{8}{3}x + 24\]Add \(4\) to both sides to isolate \(y\):\[y = \frac{8}{3}x + 28\]
05
Verify the Equation
Check if the line passes through the point \((-9, 4)\). Substitute \(x = -9\) into the equation:\[y = \frac{8}{3}(-9) + 28 = -24 + 28 = 4\]Since \(y = 4\) when \(x = -9\), the equation \(y = \frac{8}{3}x + 28\) is correct.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
Understanding the slope-intercept form is vital for diving into linear equations. This form of a line is given by the equation \(y = mx + b\), where:\
In our example, we have transformed the equation \(8x - 3y = 24\) into the form \(y = \frac{8}{3}x - 8\). Here, \(\frac{8}{3}\) is the slope and \(-8\) is the y-intercept. These values help us understand the original line's orientation and position in the graph.
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- \(m\) represents the slope of the line, which measures how steep the line is.\ \
- \(b\) stands for the y-intercept, which is the point where the line crosses the y-axis.\ \
In our example, we have transformed the equation \(8x - 3y = 24\) into the form \(y = \frac{8}{3}x - 8\). Here, \(\frac{8}{3}\) is the slope and \(-8\) is the y-intercept. These values help us understand the original line's orientation and position in the graph.
Point-Slope Form
The point-slope form of a linear equation is a powerful tool when you need to draft a line with a known slope passing through a specific point. It appears as \(y - y_1 = m(x - x_1)\), allowing you to efficiently plot your line using these elements:\
In the problem given, the line we needed had to be parallel to \(8x - 3y = 24\) and pass through \((-9, 4)\). Once we found the slope \(\frac{8}{3}\), we substituted directly into the point-slope form to find \(y - 4 = \frac{8}{3}(x + 9)\). With this, constructing the desired parallel line becomes a walk in the park.
- \
- \((x_1, y_1)\) is a point on the line, serving as your anchor.\ \
- \(m\) is the slope of the line, providing the angle of its ascent or descent.\ \
In the problem given, the line we needed had to be parallel to \(8x - 3y = 24\) and pass through \((-9, 4)\). Once we found the slope \(\frac{8}{3}\), we substituted directly into the point-slope form to find \(y - 4 = \frac{8}{3}(x + 9)\). With this, constructing the desired parallel line becomes a walk in the park.
Equation of a Line
Finding the equation of a line involves understanding its inherent characteristics, like the slope and specific points through which it passes. A line can be represented in multiple ways, such as the slope-intercept form and point-slope form previously discussed. Each form has its purpose: \
- The slope-intercept form \(y = mx + b\) emphasizes the slope and y-intercept for easier graphing. \ - The point-slope form \(y - y_1 = m(x - x_1)\) focuses on constructing the line based on a particular point and slope.\
In our exercise, after using the point-slope equation \(y - 4 = \frac{8}{3}(x + 9)\), we then transformed it into slope-intercept form: \(y = \frac{8}{3}x + 28\).\
This equation simplifies the understanding of the line's behavior and confirms that it traverses through \,\((-9, 4)\). Knowing these connections not only aids in comprehension but also empowers future scenarios where such techniques are needed.
- The slope-intercept form \(y = mx + b\) emphasizes the slope and y-intercept for easier graphing. \ - The point-slope form \(y - y_1 = m(x - x_1)\) focuses on constructing the line based on a particular point and slope.\
In our exercise, after using the point-slope equation \(y - 4 = \frac{8}{3}(x + 9)\), we then transformed it into slope-intercept form: \(y = \frac{8}{3}x + 28\).\
This equation simplifies the understanding of the line's behavior and confirms that it traverses through \,\((-9, 4)\). Knowing these connections not only aids in comprehension but also empowers future scenarios where such techniques are needed.