Chapter 12: Problem 43
At what points of \(\mathbb{R}^{2}\) are the following functions continuous? $$f(x, y)=\sin x y$$
/*! 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}
Learning Materials
Features
Discover
Chapter 12: Problem 43
At what points of \(\mathbb{R}^{2}\) are the following functions continuous? $$f(x, y)=\sin x y$$
All the tools & learning materials you need for study success - in one app.
Get started for free
What point on the plane \(x-y+z=2\) is closest to the point (1,1,1)\(?\)
Suppose you follow the spiral path \(C: x=\cos t, y\) \(=\sin t, z=\) \(t,\) for \(t \geq 0,\) through the domain of the function \(w=f(x, y, z)=x y z /\left(z^{2}+1\right)\) a. Find \(w^{\prime}(t)\) along \(C\) b. Estimate the point \((x, y, z)\) on \(C\) at which \(w\) has its maximum value.
The equation \(x^{2 n}+y^{2 n}+z^{2 n}=1,\) where \(n\) is a positive integer, describes a flattened sphere. Define the extreme points to be the points on the flattened sphere with a maximum distance from the origin. a. Find all the extreme points on the flattened sphere with \(n=2\) What is the distance between the extreme points and the origin? b. Find all the extreme points on the flattened sphere for integers \(n>2 .\) What is the distance between the extreme points and the origin? c. Give the location of the extreme points in the limit as \(n \rightarrow \infty\). What is the limiting distance between the extreme points and the origin as \(n \rightarrow \infty ?\)
Traveling waves (for example, water waves or electromagnetic waves) exhibit periodic motion in both time and position. In one dimension, some types of wave motion are governed by the one-dimensional wave equation $$\frac{\partial^{2} u}{\partial t^{2}}=c^{2} \frac{\partial^{2} u}{\partial x^{2}},$$ where \(u(x, t)\) is the height or displacement of the wave surface at position \(x\) and time \(t,\) and \(c\) is the constant speed of the wave. Show that the following functions are solutions of the wave equation. $$u(x, t)=\cos (2(x+c t))$$
The flow of heat along a thin conducting bar is governed by the one- dimensional heat equation (with analogs for thin plates in two dimensions and for solids in three dimensions) $$\frac{\partial u}{\partial t}=k \frac{\partial^{2} u}{\partial x^{2}},$$ where \(u\) is a measure of the temperature at a location \(x\) on the bar at time t and the positive constant \(k\) is related to the conductivity of the material. Show that the following functions satisfy the heat equation with \(k=1\). \(u(x, t)=A e^{-\alpha^{2} t} \cos a x,\) for any real numbers \(a\) and \(A\)
What do you think about this solution?
We value your feedback to improve our textbook solutions.