Chapter 1: Problem 24
Finding Equations of Lines Find an equation of the line that satisfies the given conditions. Slope \(\frac{2}{5} ; \quad y\)-intercept 4
Short Answer
Expert verified
The line's equation is \( y = \frac{2}{5}x + 4 \).
Step by step solution
01
Identify the Formula for a Line Equation
To find the equation of a line, we use the slope-intercept form of the line equation: \( y = mx + b \). Here, \( m \) represents the slope of the line and \( b \) represents the y-intercept.
02
Substitute the Given Slope
We know from the problem that the slope \( m \) is \( \frac{2}{5} \). Substitute \( m = \frac{2}{5} \) into the formula. This gives us \( y = \frac{2}{5}x + b \).
03
Substitute the Given Y-Intercept
The problem states that the y-intercept \( b \) is 4. Substitute \( b = 4 \) into the equation. This modifies the equation to \( y = \frac{2}{5}x + 4 \).
04
Finalize the Line Equation
Now that we have substituted both the slope and y-intercept, the equation of the line is finalized as \( y = \frac{2}{5}x + 4 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
One of the simplest and most commonly used forms to express the equation of a line is the slope-intercept form. It is expressed as \( y = mx + b \).
Here, \( y \) represents the dependent variable or the output of the function for a given \( x \), which is the independent variable or the input. The form clearly shows the slope \( m \) and the y-intercept \( b \), making it easy to visualize and graph linear equations.
Using the slope-intercept form is advantageous because
Here, \( y \) represents the dependent variable or the output of the function for a given \( x \), which is the independent variable or the input. The form clearly shows the slope \( m \) and the y-intercept \( b \), making it easy to visualize and graph linear equations.
Using the slope-intercept form is advantageous because
- It provides direct information about the steepness and direction of the line through the slope \( m \).
- It clearly displays the point, \((0, b)\), where the line crosses the y-axis.
Slope
Slope, denoted by \( m \) in the slope-intercept form, is a measure of the steepness and direction of a line. It represents the ratio of the vertical change (rise) to the horizontal change (run) between two points on the line.
Mathematically, this is given as:
\[m = \frac{\text{rise}}{\text{run}} = \frac{y_2 - y_1}{x_2 - x_1}\]
A positive slope means the line is rising from left to right, while a negative slope means the line is falling. A zero slope represents a horizontal line, and an undefined slope indicates a vertical line.
Mathematically, this is given as:
\[m = \frac{\text{rise}}{\text{run}} = \frac{y_2 - y_1}{x_2 - x_1}\]
A positive slope means the line is rising from left to right, while a negative slope means the line is falling. A zero slope represents a horizontal line, and an undefined slope indicates a vertical line.
- In our example, the slope is \( \frac{2}{5} \), indicating that for every five units we move horizontally, the line rises by two units.
- Slope is crucial for determining how much \( y \) changes with a change in \( x \).
Y-Intercept
The y-intercept is the point where the line crosses the y-axis. In the slope-intercept form \( y = mx + b \), the y-intercept is represented by \( b \).
This tells us the value of \( y \) when \( x \) is zero, that is, the starting point of the line on the vertical axis. Thus, the y-intercept is instrumental in graphing the line, as it provides a fixed point through which the line passes.
For the exercise we examined:
This tells us the value of \( y \) when \( x \) is zero, that is, the starting point of the line on the vertical axis. Thus, the y-intercept is instrumental in graphing the line, as it provides a fixed point through which the line passes.
For the exercise we examined:
- The y-intercept is 4.
- This means that when \( x = 0 \), \( y \) equals 4.
Equation of a Line
An equation of a line is an algebraic expression that defines a straight line on a coordinate plane. It unifies the slope and y-intercept concepts we discussed.Lines communicate a constant rate of change, which is vital in a variety of fields, from physics to economics.The general procedure to find the equation of a line uses:
- The slope \( m \), which we've set as \( \frac{2}{5} \) in our problem.
- The y-intercept \( b \), here given as 4.