Chapter 3: Problem 25
Use intercepts and a checkpoint to graph equation. \(-x+4 y=6\)
Short Answer
Expert verified
The line representing the equation \(-x + 4y = 6\) will pass through the three points (-6, 0), (0, 1.5), and (1, 1.75). So these are the intercepts and one checkpoint used to graph this equation.
Step by step solution
01
Find the x-intercept
To find the x-intercept, set \(y = 0\) in the equation and solve for x. This will give the point at which the graph intersects the x-axis. So, when y is zero, the equation becomes: \(-x + 4 * 0 = 6\). Solving this equation for x gives \(x = -6\). So, the x-intercept is at (-6, 0)
02
Find the y-intercept
The y-intercept is found in a similar manner by setting \(x = 0\) in the equation. Hence, the equation becomes: \(0 + 4y = 6\). Solving this equation for y gives \(y = 1.5\). So, the y-intercept is at (0, 1.5).
03
Choose a check point
Now that we have the intercepts, we can choose a checkpoint. It’s a good choice to take a point that is convenient to use. The origin (0,0) is often a good checkpoint to start from if it is not on the line. However, in this case the y-intercept is at (0, 1.5), so the point (0,0) is on the line. A suitable point could be x = 1. Replace x = 1 in the original equation: \(-1 + 4y = 6\), solving this for y gives \(y=7/4\) or 1.75. So, the point (1, 1.75) is on the graph.
04
Graph the function
Plot the intercepts and the checkpoint on the coordinate plane, and draw a line that passes through them to form the graph. By connecting the points (-6, 0), (0, 1.5), and (1, 1.75), graph the function. The line drawn should pass through these three points and extend beyond them in both directions.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the X-Intercept
The x-intercept is a fundamental concept when working with linear equations. It represents the point where the graph of the equation crosses the x-axis. To find this point, you set the value of y to zero and solve the equation for x.
In our example equation, \[ -x + 4y = 6 \] we find the x-intercept by substituting y with 0:- Solve \[ -x + 4(0) = 6 \]- This simplifies to \[ -x = 6 \]- Solving for x gives us \[ x = -6 \]. Thus, the x-intercept is (-6, 0).Understanding this point is important since it indicates where the graph cuts the x-axis.
In our example equation, \[ -x + 4y = 6 \] we find the x-intercept by substituting y with 0:- Solve \[ -x + 4(0) = 6 \]- This simplifies to \[ -x = 6 \]- Solving for x gives us \[ x = -6 \]. Thus, the x-intercept is (-6, 0).Understanding this point is important since it indicates where the graph cuts the x-axis.
Identifying the Y-Intercept
The y-intercept is equally important for understanding the shape and position of a graph. It is the point where the graph crosses the y-axis. To find this, we set x to zero and solve for y.
Taking our example equation: \[ -x + 4y = 6 \]we find the y-intercept by substituting x with 0:- Solve \[ 0 + 4y = 6 \]- This simplifies to \[ 4y = 6 \]- Solve for y, leading to \[ y = \frac{3}{2} \]- Therefore, the y-intercept is (0, 1.5).The y-intercept helps to locate where the line meets the y-axis on the graph.
Taking our example equation: \[ -x + 4y = 6 \]we find the y-intercept by substituting x with 0:- Solve \[ 0 + 4y = 6 \]- This simplifies to \[ 4y = 6 \]- Solve for y, leading to \[ y = \frac{3}{2} \]- Therefore, the y-intercept is (0, 1.5).The y-intercept helps to locate where the line meets the y-axis on the graph.
Steps for Graphing a Linear Equation
Graphing a linear equation involves plotting points and drawing a line through them. Understanding the graph of a linear equation helps visualize solutions and function behavior.
Here's a step-by-step
Here's a step-by-step
- Identify Intercepts: Start by finding both the x-intercept and y-intercept. These points are where the line crosses the axes and are crucial for understanding the graph's orientation.
- Select a Checkpoint: A third point on the line helps ensure accuracy in plotting. Compute this by substituting another value for x or y, as was done with x = 1 in our example. This extra point aids in drawing a precise line.
- Plot Points on the Graph: Use the calculated intercepts and the checkpoint to plot on the coordinate plane. Mark them clearly.
- Draw the Line: Carefully connect these plotted points, extending the line beyond the given points to represent the equation fully. This line represents all solutions of the equation.
Understanding the Coordinate Plane
A coordinate plane is a foundational concept in graphing linear equations. It's a two-dimensional surface used to plot points, lines, and curves.
Key features:
Key features:
- Axes: The plane consists of two perpendicular lines — the x-axis (horizontal) and the y-axis (vertical). These axes intersect at the origin (0,0).
- Quadrants: The plane is divided into four sections or quadrants, which help in identifying the position of points like intercepts.
- Coordinates: Each point on the plane has a pair of numbers known as coordinates, with the first number indicating position along the x-axis and the second along the y-axis.