Chapter 8: Problem 56
Find the equation of each line. Write the equation using standard notation unless indicated otherwise. $$ \text { Slope }-\frac{3}{5} \text { ; through }(4,-1) $$
Short Answer
Expert verified
The equation of the line is \(-3x + 5y = 7\).
Step by step solution
01
Identify the Slope-Intercept Format
The slope-intercept form of the equation of a line is given by \( y = mx + c \), where \( m \) is the slope of the line and \( c \) is the y-intercept.
02
Substitute the Slope and Point into the Equation
Given that the slope \( m = -\frac{3}{5} \) and the point is \((4, -1)\), substitute these into the slope-intercept form: \(-1 = -\frac{3}{5}(4) + c\).
03
Solve for the Y-Intercept
Calculate \(-\frac{3}{5} \times 4 = -\frac{12}{5}\). Substitute this into the equation to find \( c \): \[-1 = -\frac{12}{5} + c\].Convert \(-1\) into a fraction with the same denominator: \(-\frac{5}{5}\). Solve for \( c \): \[c = -1 + \frac{12}{5} = \frac{7}{5}\].
04
Write the Equation in Slope-Intercept Form
Now that we know \( c = \frac{7}{5} \), plug \( m \) and \( c \) back into the equation: \[y = -\frac{3}{5}x + \frac{7}{5}\].
05
Convert to Standard Form
The standard form of the line's equation is \( Ax + By = C \). Rearrange the slope-intercept equation into standard form: Start with \( -\frac{3}{5}x + y = \frac{7}{5}\). Multiply the entire equation by 5 to clear fractions: \(-3x + 5y = 7\).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
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 very popular way to express the equation of a line. It is written as \( y = mx + c \). Here, \( m \) stands for the slope of the line, which tells us how steeply the line inclines or declines. The \( c \) represents the y-intercept, which is the point where the line crosses the y-axis.
When working with the slope-intercept form:
When working with the slope-intercept form:
- The value of \( m \) determines the direction and steepness of the line. A positive \( m \) means an upward slope, while a negative \( m \) indicates a downward slope.
- The value of \( c \) gives a clear indication of where the line intersects the y-axis, which means when \( x = 0 \).
Standard Form
The standard form of a linear equation is expressed as \( Ax + By = C \), where \( A \), \( B \), and \( C \) are integers, and \( A \) and \( B \) should not both be zero. This form is very structured, which makes it useful in situations where you need to find intercepts or manipulate equation parts.
A key advantage of the standard form is:
A key advantage of the standard form is:
- It's easy to solve for both x- and y-intercepts by plugging zero in for the other variable.
- All terms are compared directly on one side, which assists in solving equations simultaneously or analyzing relationships between lines.
Solving for Y-Intercept
Finding the y-intercept \( c \) in the equation \( y = mx + c \) involves substituting a known slope and a point the line passes through. If you have a slope \( m \) and a point \((x_1, y_1)\), plug them into the slope-intercept form: \(y_1 = mx_1 + c\). Then solve for \( c \).
For example, given a slope \( m = -\frac{3}{5} \) and the point \((4, -1)\):
For example, given a slope \( m = -\frac{3}{5} \) and the point \((4, -1)\):
- Substitute into the equation: \(-1 = -\frac{3}{5}(4) + c\).
- Calculate the multiplication: \(-\frac{3}{5} \times 4 = -\frac{12}{5}\).
- Solve for \( c \) by isolating it: \(c = -1 + \frac{12}{5} = \frac{7}{5}\).
Rearranging Equations
Rearranging involves transforming one form of an equation to another while maintaining its equality. It's crucial when you need to express an equation in a specific format, like turning a slope-intercept form into a standard form.
Here's a basic approach to rearranging equations:
Here's a basic approach to rearranging equations:
- Identify your starting equation and your target format. For example, starting with \( y = mx + c \) and changing it to \( Ax + By = C \).
- Move all terms involving \( x \) and \( y \) to one side by performing operations like addition, subtraction, multiplication, or division that transform the equation correctly.
- Simplify the equation by clearing out fractions or decimals. Here, multiplying through by a common denominator helps eliminate fractions, leading to integer coefficients.
- Check your work by ensuring that all terms are balanced and the equation remains true to its original relationships.