/*! 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 29 Use the Two-Path Test to prove t... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Use the Two-Path Test to prove that the following limits do not exist. $$\lim _{(x, y) \rightarrow(0,0)} \frac{x+2 y}{x-2 y}$$

Short Answer

Expert verified
Answer: No, the limit does not exist.

Step by step solution

01

Approach along the x-axis (y = 0)

When approaching along the x-axis, we set y = 0 and evaluate the limit as x approaches 0: $$\lim _{x \rightarrow 0} \frac{x+2(0)}{x-2(0)} = \lim _{x \rightarrow 0} \frac{x}{x}$$ Since the function simplifies into a constant, we can directly substitute the limit point: $$\frac{x}{x} = 1$$ So the limit along the x-axis is 1.
02

Approach along the y-axis (x = 0)

When approaching along the y-axis, we set x = 0 and evaluate the limit as y approaches 0: $$\lim _{y \rightarrow 0} \frac{0+2 y}{0-2 y} = \lim _{y \rightarrow 0} \frac{2y}{-2y}$$ Since the function simplifies into a constant, we can directly substitute the limit point: $$\frac{2y}{-2y} = -1$$ So the limit along the y-axis is -1. Since the limits along the x-axis and y-axis are different (1 and -1), we can conclude, by using the Two-Path Test, that the given limit does not exist: $$\lim _{(x, y) \rightarrow(0,0)} \frac{x+2 y}{x-2 y}$$ does not exist.

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.

Limits
Limits in mathematics are foundational concepts that describe the behavior of a function as its input approaches a particular point. For functions of a single variable, the limit looks at what value the output gets closer to as the input nears a particular value. In this exercise, we explore multivariable limits, examining how the function behaves as both variables get closer to a certain point, in this case, (0,0). The Two-Path Test is a common technique used to demonstrate when a multivariable limit does not exist. By calculating limits along different paths (like the x-axis and y-axis in the problem), we check if these paths lead to the same limit value. If they don’t, it means the overall limit doesn't exist. This test is important because multivariable functions can behave differently than single-variable functions as they approach a point. Seeing different limits along different paths directly indicates that the function lacks a single limit at that point.
Multivariable Calculus
Multivariable calculus is an extension of calculus involving multiple variables. While single-variable calculus focuses on functions of one variable, multivariable calculus deals with functions of more than one variable, like in our exercise with both x and y. This branch of calculus introduces new concepts such as partial derivatives, multiple integrals, and multivariable limits. These tools help analyze functions that depend on several inputs or dimensions. In the context of limits, multivariable calculus seeks to understand how a function behaves as its inputs approach a specific point from all possible directions. The complexity increases due to the addition of dimensions, which is why techniques like the Two-Path Test are necessary. They help us determine whether or not a well-defined limit exists for any point given the multiple directions from which one can approach.
Continuity
Continuity in calculus describes a function that is seamless or without gaps at a certain point. For a function of a single variable, continuity means that the limit of the function as it approaches a point is equal to the function's value at that point. In multivariable calculus, continuity requires a bit more consideration. A function is continuous at a point if its limit exists and equals its value at that point from all directions. The exercise showcases an example where the limit does not exist when approaching (0,0), which implies the function is not continuous at that point. Mathematically, this lack of continuity is well illustrated when the result differs along different paths. This is significant as it indicates either changes or irregularities in behavior of the function or potential discontinuities, which are crucial when studying real-world applications involving multiple variables.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Geometric and arithmetic means Given positive numbers \(x_{1}, \ldots, x_{n},\) prove that the geometric mean \(\left(x_{1} x_{2} \cdots x_{n}\right)^{1 / n}\) is no greater than the arithmetic mean \(\frac{x_{1}+\cdots+x_{n}}{n}\) in the following cases. a. Find the maximum value of \(x y z,\) subject to \(x+y+z=k\) where \(k\) is a positive real number and \(x>0, y>0,\) and Use the result to prove that $$(x y z)^{1 / 3} \leq \frac{x+y+z}{3}$$ b. Generalize part (a) and show that$$\left(x_{1} x_{2} \cdots x_{n}\right)^{1 / n} \leq \frac{x_{1}+\cdots+x_{n}}{n$$

Probability of at least one encounter Suppose in a large group of people, a fraction \(0 \leq r \leq 1\) of the people have flu. The probability that in \(n\) random encounters you will meet at least one person with flu is \(P=f(n, r)=1-(1-r)^{n} .\) Although \(n\) is a positive integer, regard it as a positive real number. a. Compute \(f_{r}\) and \(f_{n^{*}}\) b. How sensitive is the probability \(P\) to the flu rate \(r ?\) Suppose you meet \(n=20\) people. Approximately how much does the probability \(P\) increase if the flu rate increases from \(r=0.1\) to \(r=0.11(\text { with } n \text { fixed }) ?\) c. Approximately how much does the probability \(P\) increase if the flu rate increases from \(r=0.9\) to \(r=0.91\) with \(n=20 ?\) d. Interpret the results of parts (b) and (c).

Explain why or why not Determine whether the following statements are true and give an explanation or counterexample. a. The planes tangent to the cylinder \(x^{2}+y^{2}=1\) in \(R^{3}\) all have the form \(a x+b z+c=0\) b. Suppose \(w=x y / z,\) for \(x>0, y>0,\) and \(z>0 .\) A decrease in \(z\) with \(x\) and \(y\) fixed results in an increase in \(w\) c. The gradient \(\nabla F(a, b, c)\) lies in the plane tangent to the surface \(F(x, y, z)=0\) at \((a, b, c)\)

Use Lagrange multipliers to find these values. \(f(x, y, z)=(x y z)^{1 / 2}\) subject to \(x+y+z=1\) with \(x \geq 0\) \(y \geq 0, z \geq 0\)

Use what you learned about surfaces in Sections 13.5 and 13.6 to sketch a graph of the following functions. In each case, identify the surface and state the domain and range of the function. $$G(x, y)=-\sqrt{1+x^{2}+y^{2}}$$

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.