Chapter 7: Problem 17
Graph each equation using the slope and \(y\) -intercept. $$y=2 x-3$$
Short Answer
Expert verified
Plot the y-intercept at (0, -3) and use slope 2 to plot point (1, -1); connect the points with a line.
Step by step solution
01
Identify the slope and y-intercept
In the equation \(y = 2x - 3\), the slope \(m\) is 2 and the \(y\)-intercept \(b\) is -3. The slope tells us that for every increase of 1 in \(x\), \(y\) increases by 2. The \(y\)-intercept tells where the line crosses the \(y\)-axis.
02
Plot the y-intercept
Start by plotting the \(y\)-intercept (0, -3) on the graph. This point is where the line will intersect the \(y\)-axis.
03
Use the slope to find another point
From the \(y\)-intercept (0, -3), use the slope to find another point on the line. Since the slope is 2, move up 2 units and right 1 unit to reach the point (1, -1). Plot this point on the graph.
04
Draw the line
Connect the two points, (0, -3) and (1, -1), with a straight line. Extend the line in both directions, adding arrowheads to indicate that it continues indefinitely.
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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 makes graphing much simpler. This form is written as \( y = mx + b \). In it, \( m \) represents the slope of the line, and \( b \) represents the \( y \)-intercept. This format allows you to quickly understand how steep a line is and where it crosses the \( y \)-axis. Knowing these two components is crucial as it provides a direct insight into the behavior of the line on a graph without needing to create a table of values. Remember, the higher the absolute value of the slope, the steeper the line becomes. Meanwhile, the \( y \)-intercept directly corresponds to a specific point on the graph, making it an anchor for plotting.
Plotting Points
Plotting points is an essential skill for visualizing equations graphically. Once you have your slope and \( y \)-intercept from a linear equation, you can start plotting. Begin by plotting the \( y \)-intercept point, which gives you a solid starting location. From there, use the slope to determine the next point.
- Mark the \( y \)-intercept on the graph.
- From the \( y \)-intercept, use the slope to find another point.
Slope of a Line
The slope of a line is a measure of its steepness, indicating how much the line rises or falls as it moves horizontally across the graph. In the slope-intercept form \( y = mx + b \), the slope is represented by \( m \).
- A positive slope means the line rises as it moves from left to right.
- A negative slope indicates the line falls as it moves from left to right.
- If the slope is zero, the line is perfectly horizontal.
- A vertical line has an undefined slope.
y-Intercept
The \( y \)-intercept is a crucial element when graphing linear equations. It is the point where the line crosses the \( y \)-axis. In the equation \( y = mx + b \), the \( y \)-intercept is denoted by \( b \). This value gives the starting point for the graph in the vertical direction.
- In our example \( y = 2x - 3 \), the \( y \)-intercept \( b \) is -3, meaning the line crosses the \( y \)-axis at (0, -3).
- The intercept shows the initial value of \( y \) when \( x \) is zero.