Chapter 3: Problem 2
Use the slope-intercept form to graph each equation. $$ y=-4 x-1 $$
Short Answer
Expert verified
Plot \((0, -1)\), use a slope of -4 to find another point, and draw the line.
Step by step solution
01
Identify the Slope and Y-intercept
The equation given is \( y = -4x - 1 \). This is in the slope-intercept form \( y = mx + b \). Here, \( m \), the slope, is \(-4\), and \( b \), the y-intercept, is \(-1\).
02
Plot the Y-intercept
To start graphing, plot the y-intercept on the graph. This is the point where the line crosses the y-axis. For \( b = -1 \), mark the point \((0, -1)\) on the graph.
03
Use the Slope to Determine the Next Point
The slope \( m = -4 \) can be expressed as \(-4/1\), meaning for every 1 unit you move to the right on the x-axis, move 4 units down on the y-axis. From the y-intercept \((0, -1)\), move to the right 1 unit to \( x = 1 \), then 4 units down to \( y = -5 \). Plot the point \((1, -5)\) on the graph.
04
Draw the Line
Connect the points \((0, -1)\) and \((1, -5)\) with a straight line. Extend the line across the graph to represent all the solutions to the equation \( y = -4x - 1 \).
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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 is a fundamental skill in algebra, allowing you to visualize relationships between variables. To graph a linear equation in the slope-intercept form, start by identifying the two main components: the slope and the y-intercept. This form is given by the equation \( y = mx + b \), where \( m \) represents the slope and \( b \) the y-intercept.
Steps to Graphing a Linear Equation:
Steps to Graphing a Linear Equation:
- Identify the Slope and Y-Intercept: Recognizing these components is key. They give you the starting point and direction of the line.
- Plot the Y-Intercept: Start by plotting the y-intercept, this is where the line will cross the y-axis.
- Use the Slope: From the y-intercept, use the slope to find another point on the line.
- Draw the Line: Connect the points to form a straight line extending across the graph.
Slope
The slope is a key concept in understanding linear equations, representing the rate at which one quantity changes relative to another. It is often denoted by the letter \( m \) in equations. The slope indicates the steepness and the direction of the line on a graph.
Understanding the Slope:
Understanding the Slope:
- Positive Slope: When the line ascends from left to right, indicating a positive rate of change.
- Negative Slope: A line that descends from left to right signals a negative rate of change, as seen with a slope of \(-4\) as in our example equation.
- Zero Slope: A horizontal line indicative of no change in \( y \) as \( x \) changes.
- Undefined Slope: A vertical line showing an undefined or infinite change.
Y-Intercept
The y-intercept is a crucial element of the slope-intercept form, marking the point where the line crosses the y-axis. It is symbolized by \( b \) in the equation \( y = mx + b \). Determining and plotting the y-intercept provides the starting point for graphing the entire line.
Importance of the Y-Intercept:
Importance of the Y-Intercept:
- Starting Point: This point, usually written as \((0, b)\), is where the line meets the y-axis.
- Easy to Plot: Even if the slope is complex, the y-intercept gives a simple coordinate to begin your graph.
- Provides Context: It represents the value of y when x is zero, offering practical understanding like initial conditions in real-world scenarios.