/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 94 A line with slope \(m\) passes t... [FREE SOLUTION] | 91Ó°ÊÓ

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A line with slope \(m\) passes through the point \((0,-2)\). (a) Write the distance \(d\) between the line and the point \((4,2)\) as a function of \(m\). (b) Use a graphing utility to graph the equation in part (a). (c) Find \(\lim _{m \rightarrow \infty} d(m)\) and \(\lim _{m \rightarrow-\infty} d(m) .\) Interpret the results geometrically.

Short Answer

Expert verified
The function of the distance between the point and the line in terms of the slope is \(d(m) = \frac{|4m - 4|}{\sqrt{m^2 + 1}}\). When the slope of the line approaches \(+\infty\) or \(-\infty\), the distance between the line and the point becomes 4.

Step by step solution

01

Equation of the line

Firstly, the equation of the line which goes through the point \((0, -2)\) and has slope \(m\) will be \(y = mx - 2\). The reason is that a linear equation is usually of the form \(y = mx + b\) where \(m\) is the slope and \(b\) is the intercept with y-axis. Since the line goes through \((0, -2)\), this point is where the line intercepts y-axis, that is \(b = -2\).
02

Distance between a point and a line

The formula for the distance \(d\) from a point \((x1, y1)\) to a line \(Ax + By + C = 0\) is \(d = \frac{|Ax1 + By1 + C|}{\sqrt{A^2 + B^2}}\). Let's rewrite our line equation \(y = mx - 2\) to the form \(Ax + By + C = 0\) . So the equation of the line becomes \(mx - y - 2 = 0\). From this, we get \(A = m\), \(B = -1\) and \(C = -2\). And our point is \((4, 2)\). Replacing all into the distance formula we get \(d = \frac{|4m - 2 - 2|}{\sqrt{m^2 + 1}} = \frac{|4m - 4|}{\sqrt{m^2 + 1}}\).
03

Graph the equation

The equation in step 2 is an absolute value equation and needs to be graphed. The graph can be produced via graphing utilities which are available online and the details will not be discussed here.
04

Find the limits as m approaches infinity

Let's find \(\lim_{m\rightarrow \infty} d(m)\) and \(\lim_{m\rightarrow -\infty} d(m)\). Using algebraic techniques for finding limits we have \(\lim_{m\rightarrow \infty}d(m) = \lim_{m\rightarrow -\infty}d(m) = 4\).
05

Interpret the results geometrically

When \(m\) approaches \(+\infty\) or \(-\infty\), the line becomes almost vertical. Regardless the slope, the distance from the point \((4,2)\) to the line becomes 4 units long, regardless of the line's slope.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Linear Equations
Understanding linear equations is essential for solving problems related to distance from a point to a line. These equations represent straight lines when graphed on a coordinate plane. A linear equation typically follows a standard form of ax + by + c = 0, where a, b, and c are constants. However, they are often expressed in slope-intercept form as y = mx + b, where m represents the slope of the line and b is the y-intercept, indicating where the line crosses the y-axis.

When analyzing distances to a line, it's important to locate the slope and the y-intercept because they define the line's precise position and orientation on the plane. Additionally, converting from the slope-intercept to the standard form is necessary to apply the distance formula effectively. Without these fundamental concepts, solving the problem at hand would be nearly impossible. Practicing with various linear equations sharpens the ability to manipulate and understand their graphical representations.
Slope-Intercept Form
The slope-intercept form of a line, given by y = mx + b, is especially useful when working with distances from points to lines. In our exercise, we know our line passes through the point (0, -2), which serves as the y-intercept (b = -2). The slope, denoted by m, is a measure of how steep the line is. This form makes it easy to visualize the line on a graph and quickly deduce key attributes like the angle it forms with the x-axis.

Understanding how to use the slope-intercept form can not only aid in graphing a line but also in finding the distance to a point. By identifying the slope m, one can predict the behavior of the distance as the line tilts steeper (m approaching infinity) or flatter (m approaching negative infinity). The slope is pivotal in our understanding of how changes in the line's tilt affect the distance to any given point.
Limit of a Function
In calculus, the concept of a limit is used to describe the behavior of a function as it approaches a particular input. Limits help explain the tendencies of functions under specific conditions, even when the function itself might not yield a finite value at those conditions. When evaluating \( \lim_{m \rightarrow \infty} d(m) \) and \( \lim_{m \rightarrow -\infty} d(m) \), we're effectively analyzing the distance function's behavior as the slope tends towards extremely steep or extremely flat orientations.

In our exercise, we find that the limits as m approaches both positive and negative infinity are the same, leading to the conclusion that the distance approaches a constant value. This is a powerful use of the limit concept since it demonstrates that even though the slope becomes infinitely steep, the distance from a particular point to the line eventually stabilizes. Limits thus become crucial tools for understanding the asymptotic behavior of functions, which has practical implications in geometry and beyond.
Graphing Utilities
Graphing utilities are digital tools that help visualize mathematical concepts, particularly equations and functions. For our problem, we can use these utilities to display the distance function graphically, which can greatly enhance comprehension. These utilities handle all sorts of functions, including linear, polynomial, and trigonometric, and are invaluable for students to confirm analytical solutions visually.

Using graphing utilities, we can plot the absolute value equation found when determining the distance, allowing us to see how the distance changes as m varies. Such visual representation gives insight into why the distance from the point to the line approaches a constant value as m grows without bounds, supporting our understanding derived from the conceptual limit calculations. These utilities, therefore, are not just convenient for quick graphing; they contribute significantly to conceptual learning by allowing students to explore and interact with functions in a dynamic way.

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Most popular questions from this chapter

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