Chapter 3: Problem 95
In the following exercises, graph each line with the given point and slope. $$ (-1,-4) ; m=\frac{4}{3} $$
Short Answer
Expert verified
Graph using the point-slope equation \( y = \frac{4}{3}x - \frac{8}{3} \) and the points \((-1, -4)\) and \( (2, 0) \).
Step by step solution
01
Identify the given point and slope
The point given is \((-1, -4)\) and the slope \(m\) is \(\frac{4}{3}\).
02
Use the point-slope form of the equation of a line
The point-slope form of a line's equation is \(y - y_1 = m(x - x_1)\). Plug in the given point \((x_1, y_1) = (-1, -4)\) and the slope \(m = \frac{4}{3}\). This gives \(y + 4 = \frac{4}{3}(x + 1)\).
03
Simplify the equation to slope-intercept form
To express the equation in slope-intercept form \(y = mx + b\), first distribute the \( \frac{4}{3} \) on the right side: \(y + 4 = \frac{4}{3}x + \frac{4}{3}\). Next, isolate \(y\) by subtracting 4 from both sides to get \(y = \frac{4}{3}x + \frac{4}{3} - 4\). \-4 can be written as \(-\frac{12}{3}\), so the final form is \(y = \frac{4}{3}x - \frac{8}{3}\).
04
Plot the given point on the graph
Plot the point \((-1, -4)\) on the coordinate plane.
05
Use the slope to find another point
The slope \( \frac{4}{3} \) means for every 3 units you move to the right (positive x-direction), you move up 4 units (positive y-direction). Starting from \((-1, -4)\), moving 3 steps right to \(x = -1 + 3 = 2\) and 4 steps up to \(y = -4 + 4 = 0\), we get another point \( (2, 0) \).
06
Draw the line
Draw a straight line through the points \((-1, -4)\) and \( (2, 0) \) to graph the line.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Point-Slope Form
The point-slope form of a linear equation is useful when you have a point and a slope. The formula is
\(y - y_1 = m(x - x_1)\).
This tells you how the y-value changes with the x-value starting from a particular point \((x_1, y_1)\).
In the exercise, we start with the point \((-1, -4)\) and the slope \(m = \frac{4}{3}\).
This form helps us quickly write an equation for the line
\(y - y_1 = m(x - x_1)\).
This tells you how the y-value changes with the x-value starting from a particular point \((x_1, y_1)\).
In the exercise, we start with the point \((-1, -4)\) and the slope \(m = \frac{4}{3}\).
This form helps us quickly write an equation for the line
Slope-Intercept Form
The slope-intercept form is another way to write the equation of a line.
It is written as \(y = mx + b\).
Here, \(m\) is the slope, and \(b\) is the y-intercept where the line crosses the y-axis.
To convert from point-slope form to slope-intercept form:
For example, from \(y + 4 = \frac{4}{3}(x + 1)\), we distribute to get \(y + 4 = \frac{4}{3}x + \frac{4}{3}\).
Then we subtract 4 from both sides to find \(y\), resulting in \(y = \frac{4}{3}x - \frac{8}{3}\).
It is written as \(y = mx + b\).
Here, \(m\) is the slope, and \(b\) is the y-intercept where the line crosses the y-axis.
To convert from point-slope form to slope-intercept form:
- \t
- First, distribute the slope \(m\). \t
- Then, isolate \(y\) by moving the constant term to the other side.
For example, from \(y + 4 = \frac{4}{3}(x + 1)\), we distribute to get \(y + 4 = \frac{4}{3}x + \frac{4}{3}\).
Then we subtract 4 from both sides to find \(y\), resulting in \(y = \frac{4}{3}x - \frac{8}{3}\).
Plotting Points
Plotting points is a crucial step in graphing any line. To start:
This forms the basis of the graph.
Plotting the second point using the slope helps reinforce accuracy.
With a slope of \(\frac{4}{3}\):
- \t
- Locate the x-coordinate on the x-axis.
- From this x-coordinate, move vertically to find the y-coordinate.
\t
- \t
- Locate -1 on the x-axis.
- Move down to -4 on the y-axis and place a point.
\t
This forms the basis of the graph.
Plotting the second point using the slope helps reinforce accuracy.
With a slope of \(\frac{4}{3}\):
- \t
- Walk 3 steps to the right (positive x-direction).
- Then rise 4 steps up (positive y-direction).
\t
Graphing Lines
Graphing lines involves drawing a straight line that passes through all plotted points.
To graph the line:
This line represents all solutions to your linear equation.
In our exercise, drawing a line through points \((-1, -4)\) and \((2, 0)\) shows the graph for the equation \(y = \frac{4}{3}x - \frac{8}{3}\).
Always ensure your line extends through the whole graph to show the relationship between x and y across a range of values.
This gives a complete visual representation.
To graph the line:
- First, plot all your points.
- Then, use a ruler to draw a straight line through them.
\t
\t
This line represents all solutions to your linear equation.
In our exercise, drawing a line through points \((-1, -4)\) and \((2, 0)\) shows the graph for the equation \(y = \frac{4}{3}x - \frac{8}{3}\).
Always ensure your line extends through the whole graph to show the relationship between x and y across a range of values.
This gives a complete visual representation.