Chapter 8: Problem 1
Graph each linear function. $$ f(x)=-2 x $$
Short Answer
Expert verified
Plot points at \((0,0)\) and \((1,-2)\) to graph the line.
Step by step solution
01
Identify the Function
The function provided is \( f(x) = -2x \). This is a linear function where the coefficient of \( x \) is \(-2\), which represents the slope, and there is no constant term, meaning the y-intercept is \(0\).
02
Determine the Slope and Y-Intercept
In the equation \( y = mx + b \), \( m \) is the slope and \( b \) is the y-intercept. Here, \( m = -2 \) and \( b = 0 \). The slope of \(-2\) indicates that for every unit increase in \( x \), \( y \) decreases by 2 units.
03
Plot the Y-Intercept
Start plotting the graph by marking the y-intercept at \( (0,0) \). This is the point where the graph crosses the y-axis.
04
Use the Slope to Find Another Point
From the y-intercept \((0,0)\), use the slope \(-2\) to find another point. Move 1 unit to the right (positive x-direction) and 2 units down (negative y-direction) to arrive at the point \((1, -2)\).
05
Plot the Second Point and Draw the Line
Plot the point \((1, -2)\) on the graph. Then, draw a straight line through both points \((0,0)\) and \((1, -2)\) to complete the graph of the linear function.
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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 an essential way to express a linear function. It is written as \( y = mx + b \), where:
- \( m \) represents the slope of the line.
- \( b \) signifies the y-intercept, the point where the line crosses the y-axis.
Y-Intercept
The y-intercept is a critical concept when graphing linear functions. It is the point where the line crosses the y-axis of the graph.
This occurs when \( x = 0 \). In the slope-intercept form \( y = mx + b \), \( b \) represents the y-intercept.
For the function \( f(x) = -2x \), the y-intercept \( b \) is \(0\).
This occurs when \( x = 0 \). In the slope-intercept form \( y = mx + b \), \( b \) represents the y-intercept.
For the function \( f(x) = -2x \), the y-intercept \( b \) is \(0\).
- This means the graph will pass through the origin, the point \((0,0)\).
- Identifying the y-intercept is the first step in plotting the graph of a linear function.
Plotting Points
Plotting points is a straightforward yet vital step in graphing linear functions. Once the y-intercept is established, the slope guides the placement of additional points.
The slope, defined as \( m \), tells you how to move from one point to another on the graph.
The slope, defined as \( m \), tells you how to move from one point to another on the graph.
- In our example, the slope \(-2\) means that for every 1 unit you move to the right along the x-axis, you should move 2 units down in the y-direction.
- Starting from the y-intercept \((0,0)\), this rule takes you to the next point, \((1, -2)\).