Chapter 3: Problem 15
Use the slope-intercept form to graph each equation. See Examples 2 and 3. $$ y=-5 x $$
Short Answer
Expert verified
Graph the line passing through the origin and point (1,-5) with a slope of -5.
Step by step solution
01
Identify the equation form
The given equation is in the form \( y = mx + b \), which is the slope-intercept form, where \( m \) is the slope and \( b \) is the y-intercept. The equation given is \( y = -5x \).
02
Determine the slope
In the equation \( y = -5x \), the slope \( m \) is \(-5\). This means for every 1 unit increase in \( x \), \( y \) decreases by 5 units.
03
Identify the y-intercept
The y-intercept \( b \) is the constant term in the equation. Here, \( b = 0 \) since there is no constant term added to \(-5x\), which means the line crosses the y-axis at the origin (0,0).
04
Plot the y-intercept
On a coordinate grid, plot the y-intercept (0,0), which is where the line will cross the y-axis.
05
Use the slope to find another point
Starting from the y-intercept (0,0), apply the slope \(-5\). Move right 1 unit to increase \( x \) by 1, and move down 5 units to decrease \( y \) by 5. This gives the second point (1, -5).
06
Draw the line
Connect the points (0,0) and (1,-5) with a straight line extending in both directions. This line represents the graph of the equation \( y = -5x \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Linear Equations
When it comes to graphing linear equations, the slope-intercept form is a handy tool. This form is represented as \( y = mx + b \), where \( m \) is the slope, and \( b \) is the y-intercept. To graph an equation like \( y = -5x \), we start by identifying these two key components.
- First, recognize that the equation is already in slope-intercept form.
- Next, identify the slope \(-5\) and the y-intercept \(b = 0\).
- Plot the y-intercept on the graph. In this case, the point is \( (0,0) \).
Slope
The concept of slope describes the steepness and direction of a line, and it can significantly aid in graphing linear equations. The slope \( m \) in the equation \( y = mx + b \) tells us how much \( y \) changes with a unit change in \( x \). For the equation \( y = -5x \), the slope is \(-5\).
- A slope of \(-5\) means that for every unit you move to the right on the x-axis, the y-value decreases by 5 units.
- This consistent rate of change determines the angle and the direction of the line on a graph.
Y-intercept
The y-intercept \( b \) in the slope-intercept form \( y = mx + b \) indicates where the line crosses the y-axis. In our example, \( y = -5x \), there is no separate constant term added or subtracted — hence, the y-intercept is 0.
- The y-intercept is crucial because it is one of the easiest points to plot on a graph. For this equation, it is the origin \( (0,0) \).
- Once plotted, it serves as a starting point for charting additional points based on the slope's direction.