Chapter 3: Problem 49
Solve equation for \(y\) and then graph it. \(2 x+3 y=-3\)
Short Answer
Expert verified
The solution is \(y = -\frac{2}{3}x - 1\), and the graph is a line crossing the y-axis at -1 with a slope of -2/3.
Step by step solution
01
Rearrange the Equation
The original equation is given by \(2x + 3y = -3\). We want to solve for \(y\), so the first step is to isolate \(3y\) on one side of the equation. Start by subtracting \(2x\) from both sides to get: \(3y = -2x - 3\).
02
Solve for y
To solve for \(y\), divide every term in the equation \(3y = -2x - 3\) by 3. This gives us \(y = \frac{-2x - 3}{3}\). Simplifying the terms, we have \(y = -\frac{2}{3}x - 1\).
03
Identify the y-intercept and Slope for Graphing
The equation \(y = -\frac{2}{3}x - 1\) is in slope-intercept form \(y = mx + c\), where \(m\) is the slope and \(c\) is the y-intercept. Here, the slope \(m\) is \(-\frac{2}{3}\) and the y-intercept \(c\) is \(-1\).
04
Plot the y-intercept
On a graph, plot the y-intercept point, which is \((0, -1)\). This is where the line crosses the y-axis.
05
Use the Slope to Find Another Point
From the y-intercept \((0, -1)\), use the slope \(-\frac{2}{3}\) to find another point. The slope means that for every 3 units you move horizontally to the right, you move 2 units down. Starting from \((0, -1)\), moving 3 units right and 2 units down, plot another point at \((3, -3)\).
06
Draw the Line
Connect the points \((0, -1)\) and \((3, -3)\) with a straight line. Extend the line across the graph. Label the line with the equation \(y = -\frac{2}{3}x - 1\).
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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 one of the most popular ways to express a straight line. This form is given by the equation \(y = mx + c\). Here, \(m\) represents the slope of the line, and \(c\) is the y-intercept. This format is incredibly useful because it allows you to easily identify the slope and y-intercept just by looking at the equation.
It is particularly handy for graphing because you can quickly pick out where the line crosses the y-axis and how steep the line is.
Some key advantages include:
It is particularly handy for graphing because you can quickly pick out where the line crosses the y-axis and how steep the line is.
Some key advantages include:
- Simplified graphing process by identifying the slope and y-intercept.
- Facilitates easy comparisons between different lines.
- Enables the quick determination of a line's behavior and direction.
Y-Intercept
The y-intercept of a graph is the point where the line crosses the y-axis. In the slope-intercept form \(y = mx + c\), the y-intercept is represented by the term \(c\).
For example, in the equation \(y = -\frac{2}{3}x - 1\), the y-intercept is \(-1\). This means that when \(x = 0\), \(y = -1\).
Knowing the y-intercept is crucial for graphing as it gives you a starting point on the graph. To plot it:
For example, in the equation \(y = -\frac{2}{3}x - 1\), the y-intercept is \(-1\). This means that when \(x = 0\), \(y = -1\).
Knowing the y-intercept is crucial for graphing as it gives you a starting point on the graph. To plot it:
- Locate \(0\) on the x-axis (vertical line on the graph).
- Find the corresponding value of \(y\) which is the y-intercept.
- Place a point where these meet, which is at \((0, -1)\) in our example.
Graphing Lines
Graphing lines using the slope-intercept form is a straightforward process. The equation \(y = mx + c\) not only provides the y-intercept but also gives a clear representation of the slope \(m\), which guides how you plot the line.
To effectively graph a line:
To effectively graph a line:
- First, plot the y-intercept point on the graph.
- Then, use the slope to determine another point on the line. The slope \(-\frac{2}{3}\) means you move down 2 units for every 3 units you move to the right.
- From the y-intercept \((0, -1)\), apply the slope to find a second point. In this case, moving 3 units to the right and 2 units down lands on the point \((3, -3)\).
- Connect these points with a straight line that extends across the graph.