Chapter 4: Problem 40
Find an equation of the line containing the two given points. Express your answer in the indicated form. \((-3,0)\) and \((-5,1) ;\) standard form
Short Answer
Expert verified
The equation of the line containing the two given points \((-3,0)\) and \((-5,1)\) in standard form is:
\(x + 2y + 3 = 0\)
Step by step solution
01
Find the slope (m)
To find the slope of the line, we'll use the following formula:
m = \(\frac{(y2 - y1)}{(x2 - x1)}\)
Where (x1, y1) is the first point (-3,0) and (x2, y2) is the second point (-5, 1). Plug in the coordinates of the points into the formula.
m = \(\frac{(1-0)}{(-5-(-3))}\)
02
Simplify the slope expression
Now, we'll simplify the expression to find the slope:
m = \(\frac{1}{-5+3}\)
m = \(\frac{1}{-2}\)
So the slope of the line is -1/2.
03
Using the slope-intercept form
Now that we have the slope, we can use the slope-intercept form (y = mx + b) to find the y-intercept (b). Plug in the slope and the coordinates of one of the points (let's use (-3,0)) into the equation:
0 = \(-\frac{1}{2}\) * (-3) + b
04
Solve for the y-intercept (b)
Next, we'll solve for b:
0 = \(\frac{3}{2}\) + b
b = -\(\frac{3}{2}\)
So the y-intercept is -3/2.
05
Write the equation in slope-intercept form
Now that we have both the slope and y-intercept, we can write the equation of the line in slope-intercept form:
y = \(-\frac{1}{2}\)x - \(\frac{3}{2}\)
06
Convert to standard form
Finally, we'll convert the equation to standard form (Ax + By = C). To do this, we'll multiply both sides by 2 (to eliminate the fractions) and then move all terms to the left side:
2y = -x - 3
x + 2y + 3 = 0
The equation of the line containing the two given points (-3,0) and (-5,1) in standard form is:
x + 2y + 3 = 0
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
Understanding the slope-intercept form of a line is key to writing the equation of a line. The slope-intercept form is an equation written as \( y = mx + b \). Here:
For example, when you have an equation \( y = -\frac{1}{2}x - \frac{3}{2} \) from our exercise, it shows that:
- \( m \) is the slope of the line.
- \( b \) is the y-intercept, which is the point where the line crosses the y-axis.
For example, when you have an equation \( y = -\frac{1}{2}x - \frac{3}{2} \) from our exercise, it shows that:
- The slope \( m = -\frac{1}{2} \)
- The y-intercept \( b = -\frac{3}{2} \)
Standard Form
Another way to express the equation of a line is standard form, which is written as \( Ax + By = C \). In this form:
In our given exercise, the conversion from the slope-intercept to standard form resulted in:
- \( A \), \( B \), and \( C \) are integers.
- The equation describes the same line as when using the slope-intercept form.
In our given exercise, the conversion from the slope-intercept to standard form resulted in:
- \( x + 2y + 3 = 0 \)
Finding Slope
The slope of a line is a measure of its steepness and indicates the direction of the line. To find the slope between two points \( (x_1, y_1) \) and \( (x_2, y_2) \), you use the formula: \( m = \frac{y_2 - y_1}{x_2 - x_1} \).
Understanding how to find the slope is essential because it determines how the line will appear graphically and informs whether it will rise or fall.
- This formula subtracts the y-values and divides by the subtraction of x-values, indicating the rate at which y changes with respect to x.
- \( m = \frac{1 - 0}{-5 + 3} = \frac{1}{-2} \)
Understanding how to find the slope is essential because it determines how the line will appear graphically and informs whether it will rise or fall.