Chapter 3: Problem 13
Find the slope and the -intercept of the line with the given equation. See Example 1 $$ y=-5 x-8 $$
Short Answer
Expert verified
Slope: -5, Y-intercept: -8.
Step by step solution
01
Identify the Equation Format
The given equation is in the standard slope-intercept form, which is written as \(y = mx + b\). In this equation, \(m\) represents the slope, and \(b\) is the y-intercept.
02
Extract the Slope
In the equation \(y = -5x - 8\), the coefficient of \(x\) is \(-5\). This value represents the slope \(m\). Thus, the slope is \(-5\).
03
Extract the Y-Intercept
The constant term in the equation \(y = -5x - 8\) is \(-8\). This is the value of \(b\), which represents the y-intercept. Therefore, the y-intercept is \(-8\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope
The slope of a line is a measure of its steepness, indicating how much the line rises or falls as it moves from left to right. In a linear equation written in the slope-intercept form, it is denoted by the letter \(m\). The slope can be positive, negative, zero, or undefined depending on how the line angles in the coordinate plane.
- **Positive slope:** The line rises as it moves from left to right, indicating a positive change.
- **Negative slope:** The line falls as it moves from left to right, indicating a negative change, such as in our example \(y = -5x - 8\), where the slope \(m\) is \(-5\).
- **Zero slope:** A horizontal line has a zero slope because there is no rise as you move along the line.
- **Undefined slope:** A vertical line has an undefined slope because it does not move horizontally at all.
Y-Intercept
The y-intercept of a line is the point where the line crosses the y-axis on a graph. This is an important point for understanding the initial value or starting position of the line when \(x = 0\). In the slope-intercept form of a linear equation \(y = mx + b\), the y-intercept is represented by \(b\).
In the given equation \(y = -5x - 8\), the y-intercept \(b\) is \(-8\). This means that when \(x\) is 0, the value of \(y\) is \(-8\).
Some key points about y-intercepts include:
In the given equation \(y = -5x - 8\), the y-intercept \(b\) is \(-8\). This means that when \(x\) is 0, the value of \(y\) is \(-8\).
Some key points about y-intercepts include:
- It provides a starting point for graphing the line on a graph.
- It tells you the value of \(y\) at the exact moment where \(x = 0\).
- In real-world situations, it often represents a fixed starting value before any changes due to slope are accounted for.
Linear Equation
A linear equation is any equation that represents a straight line when plotted on a graph. These equations are fundamental in algebra and often serve as a base for more complex mathematical concepts. A typical linear equation is written in the slope-intercept form, \(y = mx + b\).
Here's why linear equations are crucial:
Here's why linear equations are crucial:
- **Predictability:** They allow for easy prediction of one variable based on the changes in another.
- **Simplicity:** Since they are straight lines, they are easier to work with compared to more complex curves.
- **Versatility:** Used across various fields like economics, biology, and physics to model relationships.
- The slope \(m = -5\), telling us the line decreases by 5 units in \(y\) for every 1 unit increase in \(x\).
- The y-intercept \(b = -8\), showing the line crosses the y-axis at \(-8\).