Chapter 10: Problem 46
Graph the line with the given equation. \(y=-2 x\)
Short Answer
Expert verified
Start at (0,0) and use slope -2 to plot and draw the line.
Step by step solution
01
Understand the Equation
The equation given is in the slope-intercept form, which is \( y = mx + b \). In this form, \( m \) is the slope of the line, and \( b \) is the y-intercept. For the equation \( y = -2x \), the slope \( m \) is -2 and the y-intercept \( b \) is 0.
02
Identify the Slope
The slope \( m = -2 \) indicates the ratio of the rise over the run. This means for every 1 unit you move horizontally to the right (positive direction on the x-axis), the line moves 2 units downwards vertically (negative direction on the y-axis).
03
Locate the Y-Intercept
The y-intercept \( b = 0 \) means that the line crosses the y-axis at the origin point (0,0). This is where you should start graphing the line.
04
Plotting the Line
Start at the y-intercept point (0,0). From this point, use the slope to determine the next point. Since the slope is -2, move 1 unit to the right along the x-axis, and then move 2 units downwards along the y-axis to mark the next point. Repeat this to confirm the direction of the line.
05
Draw the Line
Using a ruler, draw a straight line through the plotted points. Extend the line across the graph in both directions, making sure it accurately represents the slope and y-intercept from the equation. Label the line with its equation \( y = -2x \).
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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 of a linear equation is a straightforward way to express a line on a graph. It is written as \( y = mx + b \). This format makes it easy to identify both the slope and the y-intercept of the line.
- \( m \) represents the slope of the line. This tells us how steep the line is and the direction in which it slants.
- \( b \) stands for the y-intercept, the point where the line crosses the y-axis. It is crucial for determining where to begin graphing the line.
Y-Intercept
The y-intercept of a line, denoted by \( b \) in the slope-intercept form, is where the line meets the y-axis. It is a critical component because it serves as a starting point for graphing the line.
- If \( b \) is positive, the y-intercept is above the origin.
- If \( b \) is negative, it falls below the origin.
- When \( b = 0 \), the line crosses the origin at point (0, 0).
Slope
The slope of a line is an indicative value that dictates how the line ascends or descends on the graph. Represented by \( m \) in the slope-intercept form \( y = mx + b \), the slope is calculated as the change in y over the change in x (rise over run).
- A positive slope means the line rises as it moves from left to right.
- A negative slope, as in \( m = -2 \), signals that the line descends.
- The steeper the slope, the more dramatic the line's rise or fall.