Chapter 9: Problem 5
Graph each of the following linear and quadratic functions. $$f(x)=-3 x$$
Short Answer
Expert verified
Graph the line using slope \(-3\); it passes through \((0,0)\) and \((1,-3)\).
Step by step solution
01
Identify the Function Type
First, we need to identify the type of function we are dealing with. The given function is \( f(x) = -3x \). This is a linear function because it has the form \( y = mx + b \) where \( m \) is the slope and \( b \) is the y-intercept.
02
Determine the Slope and Y-intercept
In the function \( f(x) = -3x \), the slope \( m \) is \(-3\) and the y-intercept \( b \) is \(0\). The line will pass through the origin, meaning the point \((0,0)\). The slope tells us the line rises or falls as we move along the x-axis.
03
Plot the Y-intercept
The y-intercept is where the line crosses the y-axis. Since the y-intercept is 0, plot the point \((0,0)\) on the graph.
04
Use the Slope to Find Another Point
The slope \(-3\) means that for each unit of increase in \( x \), the value of \( y \) will decrease by 3 units. From the y-intercept \((0,0)\), move right 1 unit to \( x = 1 \) and down 3 units to \( y = -3 \), plotting the point \((1, -3)\).
05
Draw the Line
With the points \((0,0)\) and \((1,-3)\) plotted, draw a straight line through these points. This represents the graph of the function \( f(x) = -3x \). Linearity means the line continues infinitely in both directions at the same slope.
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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 fundamental way to express linear equations. It is usually written as \( y = mx + b \). Here, \( m \) stands for the slope of the line, and \( b \) is the y-intercept. The y-intercept is where the line crosses the y-axis. In this form, understanding each component is crucial for graphing a line accurately.
- The **slope** \( m \) indicates how steep the line is and in which direction it tilts.
- The **y-intercept** \( b \) shows the starting point of the line when \( x = 0 \).
Graphing Techniques
Graphing linear functions such as \( f(x) = -3x \) involves a step-by-step approach to plotting points and connecting them correctly. Start by identifying key features like the slope and y-intercept, which guide you in plotting the points on a graph.
- **Plot the y-intercept**: This is your starting point. In our function, it's at \((0,0)\).
- **Use the slope**: The slope of \(-3\) indicates that for each step right on the x-axis, you move down three units on the y-axis.
Algebra Concepts
In algebra, linear functions like \( f(x) = -3x \) require a strong grasp of basic concepts to manipulate and graph them effectively. Basics such as understanding coefficients, variables, and constants are keys to working with these equations.
- **Variables** are symbols representing unknown values, often denoted as \( x \) and \( y \).
- **Coefficients** are numbers attached to variables that show scaling; here, \(-3\) is the coefficient of \( x \).
- **Constants** are fixed values, like the y-intercept \( b \) in the slope-intercept form, which can be \(0\) or any other number.