Chapter 4: Problem 47
Graph the line containing the given point and with the given slope. $$(-2,-1) ; m=0$$
Short Answer
Expert verified
The given point is \((-2, -1)\) and the slope is \(m = 0\). Using the point-slope form, we find the equation of the line to be \(y = -1\). To graph the line, plot the y-intercept \((0, -1)\), and since the slope is 0, draw a horizontal line through the y-intercept.
Step by step solution
01
Use Point-Slope Form to Find the Line Equation
The point-slope form of a linear equation is given by: \[y - y_1 = m(x - x_1)\]
where \((x_1, y_1)\) is the given point and \(m\) is the slope. We are given \((-2, -1)\) as our point, which means \(x_1 = -2\) and \(y_1 = -1\). The slope, \(m\), is given as \(0\).
Now plug these values into the point-slope formula: \[y - (-1) = 0(x - (-2))\]
02
Simplify the Equation
Now we can simplify the equation: \[y + 1 = 0(x + 2)\]
Since 0 times any value is 0, the equation further simplifies to: \[y + 1 = 0\]
03
Solve for the Line Equation in Slope-Intercept Form
To find the final line equation, we need to solve for \(y\) and put it in the slope-intercept form, which is \(y = mx + b\), where \(m\) is the slope and \(b\) is the y-intercept.
Subtract 1 from both sides of the equation: \[y = -1\]
Now, we have our line equation: \[y = -1\]
04
Graph the Line
To graph the line, we can follow these steps:
1. Identify the slope, \(m\), and the y-intercept, \(b\), from the line equation. In this case, \(m = 0\) and \(b = -1\).
2. Plot the y-intercept, which is the point \((0, -1)\), on the graph.
3. Since the slope is 0, this means that the line is horizontal and all the points on the line will have the same y-coordinate. Therefore, every point on the line will have the form \((x, -1)\).
4. Draw a horizontal line through the y-intercept.
Now, you have graphed the line containing the point \((-2, -1)\) and with the slope \(m = 0\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Point-Slope Form
Point-slope form is a way to represent the equation of a straight line, making use of a known point on the line and its slope. It's written as \( y - y_1 = m(x - x_1) \), where \((x_1, y_1)\) is a specific point on the line and \( m \) is the slope.
This form is very useful when you have specific coordinates and the slope of a line, allowing you to plug in these values directly.
This form is very useful when you have specific coordinates and the slope of a line, allowing you to plug in these values directly.
- To start, identify your point, in this case, \((-2, -1)\), translating to \(x_1 = -2\) and \(y_1 = -1\).
- The slope \( m \) is given as \( 0 \) for this exercise.
Slope-Intercept Form
The slope-intercept form of a linear equation is familiar and straightforward, written as \( y = mx + b \). This form elegantly showcases both the slope \( m \) and the y-intercept \( b \).
It's a go-to format for graphing since it clearly shows the starting point on the y-axis and how the line rises or falls.
Here’s how it ties into our example:
It's a go-to format for graphing since it clearly shows the starting point on the y-axis and how the line rises or falls.
Here’s how it ties into our example:
- Once we had simplified the point-slope equation, we found it to be \( y = -1 \).
- This directly fits the slope-intercept form, where the slope \( m = 0 \) and the y-intercept \( b = -1 \).
Horizontal Line Equation
A horizontal line is one of the simplest forms, characterized by having a constant y-value across all points. The equation for a horizontal line in the coordinate plane takes the form \( y = b \), where \( b \) is a constant.
In our exercise, the equation \( y = -1 \) reflects a horizontal line:
In our exercise, the equation \( y = -1 \) reflects a horizontal line:
- The y-value remains consistent at \(-1\) no matter what the x-value is.
- Such a line indicates that the slope \( m \) is \( 0 \), meaning no vertical change as you move along the x-axis.
- You simply draw a straight line parallel to the x-axis at the specified y-coordinate.
- All points \((x, -1)\) for any x reside on this line.
Linear Graphs
Linear graphs depict equations of the first degree, typically in the form of straight lines across a chart. They are foundational in algebra and help in visualizing relationships between variables.
A simple way to understand linear graphs is through their basic properties:
The practice of plotting such graphs cements understanding of the relationship between algebraic expressions and their geometric representations on the coordinate plane.
A simple way to understand linear graphs is through their basic properties:
- They represent a constant rate of change, whether it's steep or flat, which is known as the slope.
- Intercepts serve as key points, with the y-intercept showing where the graph crosses the y-axis.
The practice of plotting such graphs cements understanding of the relationship between algebraic expressions and their geometric representations on the coordinate plane.