Chapter 7: Problem 22
Graph each equation using the slope and \(y\) -intercept. $$5 x+y=-3$$
Short Answer
Expert verified
Graph the line using \( y = -5x - 3 \), plot points \( (0, -3) \) and \( (1, -8) \), and draw the line through them.
Step by step solution
01
Convert to Slope-Intercept Form
The slope-intercept form of a line is given by the equation \( y = mx + b \), where \( m \) is the slope and \( b \) is the \( y \)-intercept. Start by isolating \( y \) in the given equation \( 5x + y = -3 \). Subtract \( 5x \) from both sides to get \( y = -5x - 3 \).
02
Identify the Slope and y-Intercept
The equation \( y = -5x - 3 \) is now in the slope-intercept form. Here, the slope \( m \) is \(-5\), and the \( y \)-intercept \( b \) is \(-3\). This means the line passes through the point \( (0, -3) \) and decreases by 5 units vertically for each unit it moves horizontally to the right.
03
Plot the y-Intercept
Start by plotting the \( y \)-intercept on the graph. Locate the point \( (0, -3) \) on the \( y \)-axis and mark this point on the graph. This is where the line intersects the \( y \)-axis.
04
Use the Slope to Find Another Point
From the \( y \)-intercept, use the slope \(-5\) (which can be written as \(-5/1\)) to determine another point on the line. Move 1 unit to the right (positive \( x \)-direction) and 5 units down (negative \( y \)-direction) to reach the point \( (1, -8) \). Plot this point on the graph.
05
Draw the Line
Now that you have two points, \( (0, -3) \) and \( (1, -8) \), draw a straight line through these points to represent the equation. Extend the line in both directions, making sure it crosses through both plotted points.
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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 equation in graphing linear equations. It is expressed as \( y = mx + b \), where \( m \) represents the slope, and \( b \) is the y-intercept. This makes it very straightforward to graph any line because:
- The y-intercept \( b \) tells you where the line crosses the y-axis. Simply look for \( y = b \) on this axis to start your graphing from a known point.
- The slope \( m \) indicates the steepness and the direction of the line. A positive slope means the line rises as it moves to the right, while a negative slope indicates it falls.
Graphing Techniques
Graphing linear equations can be simplified by adhering to certain techniques, especially using slope-intercept form. Here’s a straightforward approach to take:
- Plot the y-Intercept: Begin by placing the y-intercept on the y-axis. This is your starting point for the line.
- Use the Slope: Once the y-intercept is plotted, move according to the slope from this point to find another one. If the slope is \(-5\), move down 5 units for every unit you move to the right.
- Draw the Line: Once two points are known, draw a straight line through these points to extend in both directions.
Understanding Slope and Y-Intercept
The slope and y-intercept each play a specific role in describing a line. The slope, noted as \( m \), describes how the line inclines or declines. A slope of \(-5\) means that for each step to the right (positive x-direction), you descend 5 steps (negative y-direction). This sharp decline is visually represented on a graph as a line that falls steeply as you move from left to right.The y-intercept, noted as \( b \), is where the line crosses the y-axis. In the equation \( y = -5x - 3 \), it is \(-3\). This means the line will intersect the y-axis at the point \( (0, -3) \). It's the starting value of y when x is zero; think of it as a launching point for drawing the rest of the line via the slope.Together, the slope and y-intercept provide a complete picture of the line’s behavior and positioning.