Chapter 3: Problem 4
Use the slope-intercept form to graph each equation. $$ y=\frac{1}{4} x-3 $$
Short Answer
Expert verified
Graph shows a line with a y-intercept at (0, -3) and a slope of \( \frac{1}{4} \).
Step by step solution
01
Identify the Slope-Intercept Form
Recognize that the given equation, \( y = \frac{1}{4} x - 3 \), is already in the slope-intercept form \( y = mx + b \). Here \( m \) is the slope, and \( b \) is the y-intercept.
02
Determine the Slope and Y-Intercept
In the equation \( y = \frac{1}{4} x - 3 \), the slope \( m \) is \( \frac{1}{4} \) and the y-intercept \( b \) is \( -3 \). This means the line will cross the y-axis at the point (0, -3).
03
Plot the Y-Intercept on the Graph
Locate the y-intercept \( -3 \) on the y-axis and plot the point (0, -3) on the graph.
04
Use the Slope to Find Another Point
The slope \( \frac{1}{4} \) means you rise 1 unit and run 4 units. Starting from (0, -3), move up 1 unit to \( y = -2 \), and then 4 units to the right to \( x = 4 \). Plot the point (4, -2).
05
Draw the Line
Using a ruler, draw a straight line through the two points (0, -3) and (4, -2) which represents the graph of the equation \( y = \frac{1}{4} x - 3 \).
06
Verify the Line
Check if the line is correct by ensuring that it continues in the same direction as indicated by the slope \( \frac{1}{4} \), and it should reflect the equation correctly by aligning with additional calculated points such as moving 1 unit up and 4 units right from (4, -2) to (8, -1).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Linear Equations
Graphing linear equations involves taking an equation of a line and creating its graphical representation on a coordinate plane. Linear equations are usually written in the form of \( y = mx + b \), where \( m \) is the slope and \( b \) is the y-intercept. Once we have this form, it's straightforward to sketch the graph of the equation.
Using the slope-intercept form helps tremendously because it provides clear instructions on how to plot the graph. The equation tells you precisely where the line intersects the y-axis (the y-intercept), and how steep the line is (the slope).
Using the slope-intercept form helps tremendously because it provides clear instructions on how to plot the graph. The equation tells you precisely where the line intersects the y-axis (the y-intercept), and how steep the line is (the slope).
- The y-intercept \( b \) is the starting point of the graph on the y-axis.
- The slope \( m \) dictates the direction and steepness of the line.
Slope
The slope in a linear equation refers to the steepness and direction of the line. It is often represented by \( m \) in the slope-intercept form \( y = mx + b \). The slope can tell us a lot about the line:* **Positive Slope:** The line ascends from left to right.* **Negative Slope:** The line descends from left to right.* **Zero Slope:** The line is horizontal and has no vertical change.* **Undefined Slope:** The line is vertical.For the equation \( y = \frac{1}{4}x - 3 \), the slope \( \frac{1}{4} \) suggests that for every 1 unit the line moves up (or rises), it moves 4 units sideways to the right (or runs). It's like climbing steps; you climb 1 step up while moving 4 steps sideways. This gradual rise means the line isn't very steep. By understanding and using the slope, you can accurately determine the direction and inclination of the line.
Y-Intercept
The y-intercept is the point where the graph crosses the y-axis. It's an important aspect because it gives you an idea of where the line starts in a vertical context. This is represented by \( b \) in the slope-intercept form \( y = mx + b \). For example, in the equation \( y = \frac{1}{4}x - 3 \), the y-intercept is \(-3\).
This means that the line crosses the y-axis at the point (0, -3). To find it on the graph, you simply locate -3 on the y-axis and put a point there. This is your initial reference point for drawing the line.
This means that the line crosses the y-axis at the point (0, -3). To find it on the graph, you simply locate -3 on the y-axis and put a point there. This is your initial reference point for drawing the line.
- The y-intercept is straightforward to plot because it is always where \( x = 0 \).
- Knowing the y-intercept provides a quick start to graphing the equation.