Chapter 4: Problem 71
For the following exercises, sketch a line with the given features. An \(x\) -intercept (-2,0) and \(y\) -intercept of (0,4)
Short Answer
Expert verified
Draw a line through (-2,0) and (0,4).
Step by step solution
01
Understand the Problem
We need to draw a line that passes through the given intercepts: the x-intercept of (-2,0) and the y-intercept of (0,4). The x-intercept is where the line crosses the x-axis, and the y-intercept is where it crosses the y-axis.
02
Write the Equation of the Line
To find the equation of the line, use the slope-intercept form, which is \( y = mx + c \). First, find the slope \( m \) using the two points (x-intercept and y-intercept): \[ m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{4 - 0}{0 - (-2)} = \frac{4}{2} = 2 \]. Now, substitute one of the points, for example, (0,4), and the slope into the equation: \( 4 = 2 \times 0 + c \) to find c. This gives \( c = 4 \). Therefore, the equation of the line is \( y = 2x + 4 \).
03
Plot the Points on the Graph
Plot the two intercepts on a graph. The first point at \((-2, 0)\) should be on the x-axis, and the second point at \((0, 4)\) should be on the y-axis.
04
Draw the Line
Using a ruler, draw a straight line connecting the two points plotted in Step 3. Extend the line in both directions across the graph. This line represents the equation \( y = 2x + 4 \) with the specified intercepts.
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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 is a way of writing the equation of a line in the format: \( y = mx + c \). Here, \( m \) is the slope of the line, and it measures how steep the line is. It tells you how much \( y \) changes for a change in \( x \). Meanwhile, \( c \) is the \( y \)-intercept, showing where the line crosses the \( y \)-axis. This form is very convenient when you have the slope and the \( y \)-intercept, as it allows quick graphing of the line.
To use this form effectively:
To use this form effectively:
- Identify the slope \( m \) by calculating the rise over the run between two points on the line.
- Use any given \( y \)-intercept \( c \) directly to form the equation.
- Substitute the slope and intercept into the equation structure \( y = mx + c \).
X-Intercept
The \( x \)-intercept of a line is the point where the line crosses the \( x \)-axis. At this point, the value of \( y \) is zero. Knowing the \( x \)-intercept is quite useful because it gives us a concrete point where the line meets the horizontal axis. This point can be represented as \((-2, 0)\) as in the given exercise. This particular point not only aids in sketching the graph but also is vital during the calculation of the slope.
The concept of the \( x \)-intercept is crucial in:
The concept of the \( x \)-intercept is crucial in:
- Determining where on the \( x \)-axis the line will meet.
- Providing one of the two required points to determine the slope.
Y-Intercept
The \( y \)-intercept refers to the point where a line crosses the \( y \)-axis. Here, the \( x \) value is always zero. For the exercise at hand, this point is \((0, 4)\). This point is extremely useful because it features directly in the slope-intercept form of the equation, simplifying the equation's formulation.
This intercept serves several purposes:
This intercept serves several purposes:
- It provides a starting point for graphing a line since it is straightforward to locate on the \( y \)-axis.
- The \( y \) value of this intercept equals the constant \( c \) in the slope-intercept equation \( y = mx + c \).
Graphing Linear Equations
Graphing linear equations involves drawing a line on a coordinate grid following the equation format of the line. Once you have your equation in the form of \( y = mx + c \), your next step is to graph it, which requires two main steps:
- Plot the intercepts mentioned in the equation or given to you.
- Draw a straight line through the plotted points and extend it in both directions.