Chapter 2: Problem 272
Find the equation of a line with a \(y\) - intercept of \((0,2)\) and slope \(-\frac{1}{2}\).
Short Answer
Expert verified
The equation of the line is \(y = -\frac{1}{2}x + 2\).
Step by step solution
01
Identify the known variables
The slope of the line is given as \(-\frac{1}{2}\), and the y-intercept is given as the point \((0,2)\). These values will help us form the equation of the line.
02
Understand the slope-intercept form of a line
The slope-intercept form of a line is given by the equation \(y = mx + c\), where \(m\) is the slope and \(c\) is the y-intercept.
03
Substitute the known values into the slope-intercept form
Replace \(m\) in \(y = mx + c\) with the slope \(-\frac{1}{2}\) and \(c\) with the y-intercept 2. The equation becomes:\[ y = -\frac{1}{2}x + 2 \]
04
Confirm the equation
Verify that the equation \(y = -\frac{1}{2}x + 2\) correctly represents a line with the given slope and y-intercept by checking that when \(x = 0\), \(y = 2\). This confirms the y-intercept and when plotted, a slope of -\(\frac{1}{2}\) means for every increase of 1 in \(x\), \(y\) decreases by \(\frac{1}{2}\).
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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 fundamental concept in algebra. It provides a straightforward way to write the equation of a line and understand its properties. The form is represented as:
- \( y = mx + c \)
- \( y \) represents the dependent variable (usually the vertical coordinate in a graph).
- \( x \) is the independent variable (usually the horizontal coordinate).
- \( m \) is the slope of the line, showing the rate of change of \( y \) with respect to \( x \).
- \( c \) is the y-intercept, the point where the line crosses the y-axis.
Y-Intercept
The y-intercept is a crucial feature of the slope-intercept form. It tells us where the line meets the y-axis, providing a starting point for the graph of the line. Mathematically, the y-intercept occurs when \( x = 0 \). In our example, the y-intercept is 2, which is represented by the point \( (0, 2) \).
This means that the line crosses the y-axis at 2 on the graph. It's a direct indication of the line's vertical position on the coordinate plane when \( x \) has no effect. The y-intercept gives valuable information about the line's overall position and helps in sketching its graph precisely.
This means that the line crosses the y-axis at 2 on the graph. It's a direct indication of the line's vertical position on the coordinate plane when \( x \) has no effect. The y-intercept gives valuable information about the line's overall position and helps in sketching its graph precisely.
- A positive y-intercept moves the line above the origin.
- A negative y-intercept positions the line below the origin.
Slope of a Line
The slope of a line measures its steepness and direction and is one of the most important aspects of linear equations. It is calculated as the ratio of the change in \( y \) (vertical change) to the change in \( x \) (horizontal change). The formula for slope \( m \) is:
- \( m = \frac{\Delta y}{\Delta x} = \frac{y_2 - y_1}{x_2 - x_1} \)
- A positive slope indicates that as \( x \) increases, \( y \) also increases, creating an upward slant.
- A negative slope, like \(-\frac{1}{2}\), means that as \( x \) increases, \( y \) decreases, giving a downward tilt.
- A zero slope signifies a horizontal line with constant \( y \) values.