Chapter 8: Problem 13
For Problems \(13-22\), find the equation of the line that contains the two given points. Express equations in the form \(A x+B y=C\), where \(A, B\), and \(C\) are integers. \((2,3)\) and \((7,10)\)
Short Answer
Expert verified
The equation of the line is \\( 7x - 5y = -1 \\).
Step by step solution
01
Find the Slope of the Line
The slope (m) of the line through two points \( (x_1, y_1) \) and \( (x_2, y_2) \) can be found using the formula \( m = \frac{y_2 - y_1}{x_2 - x_1} \). For the points (2,3) and (7,10), this becomes \( m = \frac{10 - 3}{7 - 2} = \frac{7}{5}. \)
02
Use the Point-Slope Form
With the slope known, use the point-slope form of a line equation, \( y - y_1 = m(x - x_1) \). Choose point (2,3): \( y - 3 = \frac{7}{5}(x - 2) \). Simplifying, we have \( y - 3 = \frac{7}{5}x - \frac{14}{5} \).
03
Convert to Slope-Intercept Form
Isolate \( y \) to express the equation in slope-intercept form: \( y = \frac{7}{5}x - \frac{14}{5} + 3 \). Convert 3 to a fraction with a denominator of 5, \( y = \frac{7}{5}x - \frac{14}{5} + \frac{15}{5} \), resulting in \( y = \frac{7}{5}x + \frac{1}{5} \).
04
Clear the Fractions
Multiply the entire equation by 5 to eliminate the fractions: \( 5y = 7x + 1 \).
05
Express in Standard Form
Reorder the equation to match the \( Ax + By = C \) format. Rearrange \( 7x - 5y = -1 \) so all terms are on one side. The equation is already in the correct format.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope Calculation
Finding the slope is essential for understanding how steep a line is between two points. The slope, often represented by the letter \( m \), measures the vertical change relative to the horizontal change. You calculate the slope using the formula:
For example, if you have two points, (2,3) and (7,10), you can plug them into the formula:
- \( m = \frac{y_2 - y_1}{x_2 - x_1} \)
For example, if you have two points, (2,3) and (7,10), you can plug them into the formula:
- \( m = \frac{10 - 3}{7 - 2} = \frac{7}{5} \)
Point-Slope Form
After finding the slope, you can use one of the given points and the slope in the point-slope form of a line equation. This form is useful for writing the initial equation of a line and is expressed as:
- \( y - y_1 = m(x - x_1) \)
- \( y - 3 = \frac{7}{5}(x - 2) \)
Slope-Intercept Form
The slope-intercept form makes it easy to identify the slope and the y-intercept at a glance. The formula looks like this:
- \( y = mx + b \)
- \( y = \frac{7}{5}x + \frac{1}{5} \)
Standard Form of a Line
Sometimes you'll need the line equation in the standard form, \( Ax + By = C \), which is useful in some mathematical contexts like equations involving integers. Starting with our slope-intercept form \( y = \frac{7}{5}x + \frac{1}{5} \), we'll make this conversion.
1. Eliminate the fractions by multiplying the entire equation by 5:
1. Eliminate the fractions by multiplying the entire equation by 5:
- \( 5y = 7x + 1 \)
- \( 7x - 5y = -1 \)