Chapter 3: Problem 33
Graph each linear equation. Plot four points for each line. $$y=\frac{1}{2} x-1$$
Short Answer
Expert verified
To graph \( y = \frac{1}{2} x - 1 \), plot the points (0, -1), (2, 0), (4, 1), and (-2, -2), then draw a line through them.
Step by step solution
01
Understand the equation format
The given equation is in the slope-intercept form, which is written as \( y = mx + b \), where \( m \) is the slope and \( b \) is the y-intercept. Here, \( y = \frac{1}{2} x - 1 \), so the slope \( m = \frac{1}{2} \) and the y-intercept \( b = -1 \).
02
Find the y-intercept
The equation's y-intercept is the point where the line crosses the y-axis. This happens when \( x = 0 \). Substitute \( x = 0 \) into the equation to get \( y = \frac{1}{2}(0) - 1 = -1 \). Therefore, the y-intercept is the point (0, -1).
03
Calculate another point using the slope
The slope \( \frac{1}{2} \) indicates a rise of 1 unit for every 2 units of run. Starting from the y-intercept (0, -1), move 2 units to the right (along the x-axis) and 1 unit up. This gives the point (2, 0).
04
Calculate two more points on the line
Choose another value for \( x \). Using \( x = 4 \): \( y = \frac{1}{2}(4) - 1 = 2 - 1 = 1 \). This gives the point (4, 1). Now, choose \( x = -2 \): \( y = \frac{1}{2}(-2) - 1 = -1 - 1 = -2 \). This gives the point (-2, -2).
05
Plot the points and draw the line
Plot the four points found: (0, -1), (2, 0), (4, 1), (-2, -2) on graph paper. Draw a straight line through these points to represent the equation \( y = \frac{1}{2} x - 1 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
slope-intercept form
The slope-intercept form is a popular way to write the equation of a line. It is written as \( y = mx + b \), where:
- \( m \) is the slope of the line.
- \( b \) is the y-intercept.
plotting points
Plotting points involves finding coordinates that satisfy the linear equation and marking them on a graph. Here's a simple way to do it:
- Find the y-intercept. Convert \( x \) to 0 and solve for \( y \).
- Use the slope to find other points. Start from the y-intercept and move according to the slope.
- Choose additional values for \( x \) to calculate corresponding \( y \) values.
- The y-intercept (0, -1)
- Move 2 units right and 1 unit up to get (2, 0)
- For \( x = 4 \), \( y = 1 \), giving the point (4, 1)
- For \( x = -2 \), \( y = -2 \), giving the point (-2, -2)
y-intercept
The y-intercept is the point where the line crosses the y-axis. To find it in the equation \( y = mx + b \), set \( x \) to 0 and solve for \( y \).
For the equation \( y = \frac{1}{2} x - 1 \):
For the equation \( y = \frac{1}{2} x - 1 \):
- Set \( x = 0 \)
- \( y = \frac{1}{2}(0) - 1 \)
- This simplifies to \( y = -1 \)
calculating slope
Slope indicates the steepness of a line and is defined as the ratio of the vertical change (rise) to the horizontal change (run). It's found by identifying two points on the line:
\ \text{Slope} = \frac{\text{rise}}{\text{run}} \( m = \frac{\text{change in } y}{\text{change in } x} \)
For instance, if we start at the y-intercept (0, -1) of the equation \( y = \frac{1}{2}x - 1 \):
\ \text{Slope} = \frac{\text{rise}}{\text{run}} \( m = \frac{\text{change in } y}{\text{change in } x} \)
For instance, if we start at the y-intercept (0, -1) of the equation \( y = \frac{1}{2}x - 1 \):
- From (0, -1), we move 2 units to the right and 1 unit up.
- So, \( \text{rise} = 1 \) and \( \text{run} = 2 \)
- \( \text{Slope} = \frac{1}{2} \)