Problem 81

Question

will help you prepare for the material covered in the next section. In each exercise, graph the linear function. $$ 2 x-3 y=6 $$

Step-by-Step Solution

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Answer
The graph of the function \(2x - 3y = 6\) is a straight line with a slope of \(\frac{2}{3}\) and y-intercept of -2.
1Step 1: Convert to Slope-Intercept Form
To convert the equation \(2x - 3y = 6\) to slope-intercept form, isolate y. This can be done by first subtracting 2x from both sides of the equation to obtain \(-3y = -2x + 6\), then dividing everything by -3 to get \(y = \frac{2}{3}x - 2\)
2Step 2: Identify the Slope and the Y-Intercept
Now that the equation is in slope-intercept form, we can identify the slope (m) and the y-intercept (b). From the equation, we can see that \(m = \frac{2}{3}\) and \(b = -2\). The slope \(\frac{2}{3}\) indicates that for every 3 units moved horizontally (either left or right), the line will move 2 units vertically (up if moving to the right, down if moving to the left). The y-intercept -2 indicates that the line crosses the y-axis at the point (0, -2).
3Step 3: Sketch the Line
First, plot the y-intercept on the graph at the point (0, -2). Then, using the slope, move 3 units to the right and 2 units up from the y-intercept and make another point. Drawing a straight line through these points will give the graph of the linear function.

Key Concepts

Graphing Linear EquationsSlope-Intercept FormSlope and Y-Intercept
Graphing Linear Equations
Graphing linear equations is a valuable skill that allows you to visually represent mathematical relationships. To graph a linear equation, you first need to understand what the equation represents and how to turn it into a graph.

One of the first steps in graphing is recognizing the type of equation you are working with, typically given in a format known as the standard form. In this exercise, we start with \(2x - 3y = 6\). To easily graph this, it's best to convert it into slope-intercept form, where you'll have the equation in the form \(y = mx + b\). This makes it much easier to see how the line will appear on a graph.

Now that we have our equation in the form \(y = \frac{2}{3}x - 2\), we can get to graphing. Begin by plotting the y-intercept on the graph—and here it's \(-2\) on the y-axis. From this point, use the slope to determine the other points on the line. A handy trick for accuracy is to continue using the slope to plot several points before drawing your line through them. This ensures a straight, precise result.
Slope-Intercept Form
The slope-intercept form is a popular way to express linear equations. It is written as \(y = mx + b\) and clearly shows both the slope of the line and its y-intercept.

The slope \(m\) represents how steep the line is. It tells you how much \(y\) will change with every step you take along the \(x\)-axis. For example, in the equation \(y = \frac{2}{3}x - 2\), the slope \(\frac{2}{3}\) means when you move 3 units along the x-axis, you should move 2 units up or down on the y-axis, depending on the direction you're moving.

The y-intercept \(b\) is the point where the line crosses the y-axis. This makes the slope-intercept form particularly useful because with just one glance, you can see where to start your graph—by plotting the y-intercept—and how to continue it using the slope.
  • The y-intercept makes it easy to start your line graph immediately.
  • The slope provides a consistent pattern for drawing the line.
Slope and Y-Intercept
Understanding the slope and y-intercept plays a key role in effectively graphing a linear equation.

The **slope** is a critical component, symbolized as \(m\) in \(y = mx + b\). It defines the angle and direction of the line. A positive slope means the line inclines as it moves from left to right, while a negative slope would decline.

In our example, \(m = \frac{2}{3}\). This indicates that the line goes up 2 units for every 3 units you move to the right, creating an upwards slope.

The **y-intercept** \(b\) is equally important. It tells you where to begin plotting the line on a graph—the point where the line crosses the y-axis. Here, \(b = -2\), so you start drawing your line at the coordinate (0, -2).
  • The y-intercept is your starting point on the graph at \(x = 0\).
  • The slope will guide your direction and steepness.
Understanding these two elements will make it easier to draw accurate and meaningful line graphs.