Chapter 8: Problem 19
Solve each system by graphing. $$\begin{aligned} &3 y+2 x=6\\\ &y=-\frac{2}{3} x-1 \end{aligned}$$
Short Answer
Expert verified
The lines are parallel, and there is no solution.
Step by step solution
01
Convert equations to slope-intercept form
First, convert each equation into the slope-intercept form, which is given by \[y = mx + b\], where \( m\) is the slope and \( b\) is the y-intercept. The second equation is already in slope-intercept form \( y = -\frac{2}{3} x - 1 \). To convert the first equation, solve for \( y \): \[3y + 2x = 6\]Subtract \( 2x\) from both sides: \[3y = -2x + 6\]Divide by 3: \[y = -\frac{2}{3} x + 2\]
02
Identify the slope and y-intercept
For the first equation, \( y = -\frac{2}{3} x + 2 \), the slope \( m \) is \( -\frac{2}{3} \) and the y-intercept \( b \) is 2. For the second equation, \( y = -\frac{2}{3} x - 1 \), the slope \( m \) is \( -\frac{2}{3} \) and the y-intercept \( b \) is -1.
03
Graph the equations
Plot each line on a graph using their slopes and y-intercepts: 1. For the first equation \( y = -\frac{2}{3} x + 2 \), start at the y-intercept (0, 2). From this point, use the slope \( -\frac{2}{3} \) to plot the next points. Go down 2 units and right 3 units. 2. For the second equation \( y = -\frac{2}{3} x - 1 \), start at the y-intercept (0, -1). From this point, use the slope \( -\frac{2}{3} \) to plot the next points. Go down 2 units and right 3 units.
04
Analyze the graph
Both lines have the same slope and are therefore parallel. Parallel lines never intersect. As a result, this system of equations has no solution.
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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 is a wonderful way to understand the basic features of a line. It’s given by the formula: \[y = mx + b\].
Here, \(m\) stands for the slope which indicates the steepness of the line, and \(b\) is the y-intercept indicating where the line crosses the y-axis.
When you convert any linear equation into this form, you can easily spot the slope and the y-intercept. For example, from your exercise, we had equations: \[3y + 2x = 6 \] and \[y = -\frac{2}{3}x - 1 \].
The second equation is already in slope-intercept form. To convert the first one into this form, follow these steps:
Here, \(m\) stands for the slope which indicates the steepness of the line, and \(b\) is the y-intercept indicating where the line crosses the y-axis.
When you convert any linear equation into this form, you can easily spot the slope and the y-intercept. For example, from your exercise, we had equations: \[3y + 2x = 6 \] and \[y = -\frac{2}{3}x - 1 \].
The second equation is already in slope-intercept form. To convert the first one into this form, follow these steps:
- Solve for \(y\) by isolating it on one side of the equation.
- First, subtract \(2x\) from both sides to get: \[3y = -2x + 6 \]
- Then, divide everything by 3: \[y = -\frac{2}{3}x + 2 \]
graphing linear equations
Graphing linear equations is like drawing a roadmap of your equations! Once you know the slope and y-intercept, you can plot the line on a graph.
Let’s use the equations we converted earlier: \[y = -\frac{2}{3}x + 2 \] and \[y = -\frac{2}{3}x - 1 \].
Let’s use the equations we converted earlier: \[y = -\frac{2}{3}x + 2 \] and \[y = -\frac{2}{3}x - 1 \].
- Start by plotting the y-intercept. For the first equation, it’s (0, 2). For the second, it's (0, -1).
- From these intercept points, use the slope to find more points. The slope of \(-\frac{2}{3}\) means you go down 2 units and right 3 units from the intercept.
parallel lines and no solution
When you graph linear equations and they end up being parallel, something interesting happens.
For the system \[y = -\frac{2}{3}x + 2 \] and \[y = -\frac{2}{3}x - 1 \], you may notice both lines have the same slope \(-\frac{2}{3}\), but different y-intercepts.
Because their slopes are the same and they are not the same line, these lines are parallel and will never intersect.
For the system \[y = -\frac{2}{3}x + 2 \] and \[y = -\frac{2}{3}x - 1 \], you may notice both lines have the same slope \(-\frac{2}{3}\), but different y-intercepts.
Because their slopes are the same and they are not the same line, these lines are parallel and will never intersect.
- If the lines don’t intersect, they don’t have any points in common.
- Thus, the system of equations has no solution.