Chapter 1: Problem 80
True or False: Every line has a slope.
Short Answer
Expert verified
False.
Step by step solution
01
Understanding What a Line Is
A line is a straight one-dimensional figure having no thickness and extends infinitely in both directions. It can easily be represented by the equation of a line, typically written in the form, for example, \(y = mx + b\), where \(m\) represents the slope and \(b\) represents the y-intercept.
02
Defining Slope
The slope of a line (\(m\)) is a measure of how steep the line is. It is calculated as the ratio of the vertical change to the horizontal change between two distinct points on the line, \( \frac{y_2 - y_1}{x_2 - x_1} \), assuming \(x_1 eq x_2\).
03
Exception: Vertical Line
In the case of a vertical line, the equation is of the form \(x = c\), where \(c\) is a constant. For a vertical line, the change in \(x\) is zero (since \(x_2 - x_1 = 0\)) and the slope is undefined, as it involves division by zero.
04
Conclusion: Lines with Undefined Slope
Since lines can be vertical and have an undefined slope, not every line has a defined slope. Therefore, the statement that every line has a slope is false.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Equation of a Line
An equation of a line is a mathematical expression that describes a straight line. It's commonly written in the format of \(y = mx + b\). Here, \(m\) is the slope of the line, representing how steep or slanted the line is. The \(b\) is the y-intercept, indicating where the line crosses the y-axis.
When working with the equation of a line:
When working with the equation of a line:
- The slope \(m\) tells us the direction and angle of the line. A positive slope means the line moves upward as it goes right, while a negative slope shows it moves downward.
- The y-intercept \(b\) helps in plotting the initial point of the line on the graph where it meets the y-axis.
Undefined Slope
The term "undefined slope" comes into play when dealing with a specific type of line. In general concepts, the slope \(m\) is defined as \( \frac{\text{rise}}{\text{run}} = \frac{y_2 - y_1}{x_2 - x_1} \). However, what happens when \(x_1 = x_2\)?When this occurs, we are dealing with a vertical line. For such lines:
- The "run" or horizontal change between two points is zero, i.e., \(x_2 - x_1 = 0\).
- Mathematically, division by zero is undefined, so the slope becomes undefined.
- This is why vertical lines on a slope formula perspective have an undefined slope.
Vertical Line
A vertical line is an exception in linear equations. It is represented by an equation of the form \(x = c\), where \(c\) is a constant.Key characteristics of vertical lines include:
- They run "up and down" on the graph.
- All points on a vertical line have the same \(x\)-coordinate, which is \(c\). This lack of horizontal change results in a vertical orientation.
- These lines do not intersect the y-axis, unless at infinity, which is not typically represented in basic graph plotting.