What is Multivariable: Definition and 536 Discussions

Homework Statement Homework EquationsThe Attempt at a Solution I have attached the problem and solution. I don’t know how to do part b even I have looked at the solution. How to transform the original cartesian equation to the semi cylindral coordinate equation? Is there is systematical...

Let $h$ be a bump function that is $0$ outside $B_\epsilon^m(0)$ and posetive on its interior. Let $f$ be smooth function on $B_{2\epsilon}^m(0)$. Define $f^*(x)=h(x)f(x)$ if $x\in B_{2\epsilon}^m(0)$ and $=0$ if $x\in \mathbb{R^m}-B_\epsilon^m(0)$. I want to show that $f^*$ is smooth on...

Goodnight, How can I find a conservative field F, such that ∫F ds = 0 without C being a closed path Can i have some examples ?

calculate the work done by the force field $F(x,y)=(ye^{xy})i+(1+xe^{xy})j$ by moving a particle along the curve C described by gamma (γ):[0,1] in $R^2$, where gamma (γ)=(2t-1, t²-t)

Homework Statement From here, question C. http://tutorial.math.lamar.edu/Classes/CalcIII/Limits.aspx lim (x,y) -> (0,0) \frac {x^2y^2}{x^4 + 3y^4} Homework EquationsThe Attempt at a Solution So if we approach along the x axis, we know y will be 0, so we get lim (x,0) -> (0,0) \frac...

I am reading Hugo D. Junghenn's book: "A Course in Real Analysis" ... I am currently focused on Chapter 9: "Differentiation on \mathbb{R}^n" ... ... I need some help with another aspect of Definition 9.1.3 ... Definition 9.1.3 and the relevant accompanying text read as follows...

I am reading Hugo D. Junghenn's book: "A Course in Real Analysis" ... I am currently focused on Chapter 9: "Differentiation on ##\mathbb{R}^n##" ... ... I need some help with another aspect of Definition 9.1.3 ... Definition 9.1.3 and the relevant accompanying text read as follows: In the...

I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2: Differentiation ... ... I need help with an aspect of the proof of Proposition 2.3.2 ... ... Duistermaat and Kolk's Proposition 2.3.2 and its proof read as...

I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2: Differentiation ... ... I need help with an aspect of the proof of Proposition 2.3.2 ... ... Duistermaat and Kolk's Proposition 2.3.2 and its proof read as...

I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2: Differentiation ... ... I need help with the proof of Proposition 2.2.9 ... ... Duistermaat and Kolk's Proposition 2.2.9 read as follows: In the above text...

I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2: Differentiation ... ... I need help with another aspect of the proof of Lemma 2.2.7 (Hadamard...) ... ... Duistermaat and Kolk's Lemma 2.2.7 and its proof...

I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2: Differentiation ... ... I need help with another aspect of the proof of Lemma 2.2.7 (Hadamard...) ... ... Duistermaat and Kolk's Lemma 2.2.7 and its proof...

Differentialbility & Continuity of Multivariable Vector-Valued Functions ... D&K Lemma 2.2.7 ... I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2: Differentiation ... ... I need help with an aspect of the...

I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2: Differentiation ... ... I need help with an aspect of the proof of Lemma 2.2.7 (Hadamard...) ... ... Duistermaat and Kolk's Lemma 2.2.7 and its proof read as...

I am reading the book "Several Real Variables" by Shmuel Kantorovitz ... ... I am currently focused on Chapter 2: Derivation ... ... I need help with an aspect of Kantorovitz's definition of "differential" ... Kantorovitz's Kantorovitz's definition of "differential" reads as follows...

I am reading the book "Several Real Variables" by Shmuel Kantorovitz ... ... I am currently focused on Chapter 2: Derivation ... ... I need help with an aspect of Kantorovitz's definition of "differential" ... Kantorovitz's Kantorovitz's definition of "differential" reads as follows: Is the...

I am reading the book "Several Real Variables" by Shmuel Kantorovitz ... ... I am currently focused on Chapter 2: Derivation ... ... I need help with an aspect of Kantorovitz's Example 4 on page 66 ... Kantorovitz's Example 4 on page 66 reads as follows:In the above example, Kantorovitz...

I am reading the book "Several Real Variables" by Shmuel Kantorovitz ... ... I am currently focused on Chapter 2: Derivation ... ... I need help with an aspect of Kantorovitz's Example 4 on page 66 ... Kantorovitz's Example 4 on page 66 reads as follows: In the above example, Kantorovitz...

Consider the equation system x*e^y + y*f(z) = a x*g(x,y) +z^2 = b where f(z) and g(x,y) are differentiable functions, and a and b are constants. Suppose that the system defines x and y as differentiable functions of z. Find expressions for dx/dz and dy/dz. Any help would be appreciated...

I know there can be an infinite number of solutions when the objective function with 2 variables has an equal slope as a constraint's slope (assuming the constraint is affecting the feasible region and not a redundant constraint). How can you know there are multiple optimal solutions for...

1. Find if the limit exist: sin (x^3 + y^3) / (x + y) (x,y)-> (0,0) So I am starting solving this by using polar coordinates form and I get to lim= sin r^3 ( cos^3θ + sin^3θ) / r ( cosθ + sinθ) = lim r^2 ( cos^2Θ + sin^2Θ) My question is ok so far and how...

Hello Physics Forums! I'm in a little bit of an interesting situation. I've completed the classes offered at my school, but have been told that if I can directed-study these four courses they will provide me with a credit bearing exam for college undergraduate credit. Do you have any...

Books on multivariable calculus that I often see get good recommendations are, Vector Calculus, Linear Algebra, and Differential Forms by Hubbard and Hubbard Vector Calculus by Colley What are other good books with some material on differential forms like Hubbard and Colley? Books by Edwards...

I am going to be a freshman in college and I intend to major in astrophysics. This past year I took AP calculus AB, and I got an A and I believe I did well on the AP test (results haven't come back yet though). This morning I took my school's math placement test, and I was placed into...

Hello everyone. Iam working on a course in multivariable control theory and I stumbled over the Identity Matrix. I understand what the identity matrix is, though the use of it is a mistery... I was reading about going from state space to transfer functions and I found this expressions...

Hi guys, i´m pretty well in calculus 1 and i´m studying for the International Physics Olympiad. So I´d like to know some multivariable calculus books that cover vector calc too, are balanced (proofs are welcome) and emphasizes physical intuitions. Thank you already!

I am almost on the verge of completing single-variable Calculus, and I've got a book on the same by I. A. Maron. So, after getting a good grip on single-variable Calculus, I want to start with multivariable. Can anyone recommend me good books on multivariable Calculus with which I could begin...

Hi, I'm asking for a friend who will be majoring in chemical engineering. We have already taken Calculus I, II, and III under a course offered by a local community college. Admittedly, it was taught from stewart's series of calculus books, and we did exactly zero proofs in the class, and all...

Homework Statement Let L1 be the tangent line to r(t) at the point t = a and let L2 be the tangent line where t = b. Find the equation of the lines L1. Find the equation of the lines L1 and L2 and find the points of intersection. r(t) = <f(t), g(t), h(t)> *bolded letters are vectors Homework...

I am a student currently taking both Multivariable Calculus and Differential Equations. Instead of a final exam my teacher assigned a final project for Multivariable, and I chose to do something with Spacetime/Black holes. Within the scope of <100 hours of work, is there anything I can do with...

Find the critical points and test for relative extrema. List the critical points for which the Second Partials Test fails. f (x, y) = x^(2/3) + y^(2/3) Solution: f_x = 2/[3 (x)^1/3] f_y = 2/[3 (y)^1/3] f_xx = -2/[9 x^(4/3)] f_yy = -2/[9 y^(4/3)] f_xy = 0 I set f_x and f_y to 0 and found...

Hello. I am having a lot of trouble trying to solve/analyse this integral: $$\displaystyle \int_2^\infty \frac{x+y}{(y)(y^2-1)(\ln(x+y))} dy$$ I have tried everything with no result; it seems impossible for me to work with that natural logarithn. I have also tried to compute it, as it...

Homework Statement Compute the work of the vector field ##F(x,y)=(\frac{y}{x^2+y^2},\frac{-x}{x^2+y^2})## in the line segment that goes from (0,1) to (1,0). Homework Equations 3. The Attempt at a Solution [/B] My attempt (please let me know if there is an easier way to do this) I applied...

Homework Statement If f(x) is a scalar-valued function, show that ∂ƒ²/∂xi∂xj are the components of a Cartesian tensor of rank 2. Homework Equations N/A The Attempt at a Solution I don't even know where to begin. We began learning tensors in multivariable calculus (though I don't think this is...

Homework Statement Find the following limit: Homework EquationsThe Attempt at a Solution My lecturer has said that rational functions which are a ratio of two polynomials are continuous on R^2. He also said that the limits of continuous functions can be computed by direct substitution. The...

What does it mean for a ##f(x,y)## to be differentiable at ##(a,b)##? Do I have to somehow show ##f(x,y)-f(a,b)-\nabla f(a,b)\cdot \left( x-a,y-b \right) =0 ##? To show the function is not though, it's enough to show, using the limit definition, that the partial derivative approaching in one...

Homework Statement I have to prove some things on the Weber-Ferma problem. Here is the assignment : We want to find a point $$x$$ in the plane whose sum of weighted distances from a given set of fixed points $$y_1, ...,y_m$$ is minimized. 1-Show that there exist a global mimimum to the...

If you have a function x = x(u,t) then does u necessarily depend on x and t? so u = (x,t) For example, if x(u,t)=u^2 t it seems that because t=x/u^2 , t=t(x,u) I am having difficulty working out the general equation for dz \over dx if z=z(x,y,t) x=x(u,t) y=y(u,v,t) The chain rule...

I had posted a question earlier which this is related to, but a different equation. $$\frac{d}{dt} \int_0^t H(t,s)ds = H(t,t) + \int_0^t \frac{\partial H}{\partial t}(t,s)ds$$ This was another formula needed in a proof however I don't see how this one holds either. I tried following a proof of...

Homework Statement Hey I'm trying to prove the rigorous definition of limit for the following function: Lim (x,y) approaches (1,1) of f(x,y)=(y*(x-1)^(4/3))/((x/1)^2+abs(x)*y^2) Homework Equations abs(x^2)<abs(x^2 +y^2) The Attempt at a Solution I know the rigorous definition of limit. I...

Homework Statement Hi everybody! I'm trying to solve the following problem and I am unsure about what I did: Calculate ##\int_M f(x,y) dx dy## with ##M = \{ (x,y) \in \mathbb{R}^2: x^2 + y^2 \leq 1, x \geq 0, y \geq 0 \}## and ##f(x,y) = xy^2##. Homework Equations One equation I'd like to...

I am trying to learn all the methods of finding the limit of a multivariable function. If I have $$\lim_{{(x, y)}\to{(0,0)}} \frac{x}{x^2 + y^2}$$ I can set $y = mx$ to see if the function solely depends on $m$, in which case the limit does not exist. So I would get $$\lim_{{(x...

Hi everybody! I'm preparing an exam of "Analysis II" (that's how the subject's called in German), and I have trouble understanding how to find the limit of a multivariable function, especially when it comes to proving the uniform convergence. Here is an example given in the script of my teacher...

Hi everyone. I was working on a problem for days. The problem statement is: "Consider points P(2,1,3), Q(1,2,1), R(-1,-1,-2), S(1,-4,0). Find the shortest distance between lines PQ and RS." Now, I did the following formula: PS dot (PQ x RS) / magnitude of (PQ x RS). (For skew lines) Now...

I have $$\lim_{{(x, y)}\to{(0, 0)}} \frac{x}{x^2 + y^2}$$ We can approach the limit on the x-axis, so the values of $x$ will change and the values of $y$ will stay : $$\lim_{{x}\to{0}} \frac{x}{x^2}$$ I suppose I can take hospital's rule and get $$\lim_{{x}\to{0}} \frac{x}{x^2}$$...

I have found that multivariable limits are harder to find and/or prove that something exists. Do you have any recommendations, given questions like "find(if exists) the limit...". For example, I have no idea how to even start thinking about the following limit(if it exists or not, and if it...

Homework Statement : the question wants me to prove that the limit of f(x,y) as x approaches 1.3 and y approaches -1 is (3.3, 4.4, 0.3). f(x,y) is defined as (2y2+x, -2x+7, x+y). [/B] The attempt at a solution: This is the solution my lecturer has given. it's not very neat, sorry...

Hey all, is it possible to find a function that for $$ a,b,c.. \in \mathbb{R} $$ $$ y= f(a,b,c,..) , \hspace{5mm} y= \rho , \rho \in \mathbb{R} \hspace{2mm} for \hspace{2mm} only \hspace{2mm} 1 \hspace{2mm} set \hspace{2mm} of \hspace{2mm} a,b,c.. $$ Any help appreciated

Hi, I want to re-learn multivariable calculus, after I have learned it, not in the best possible way... and feel bad about it. I have seen the recommendations here about Hubbard/Shifrin/Fleming/Edwards. I have also seen the books by Munkres/Spivak/Apostol. I didn't really like Hubbard's book...

Homework Statement Hey guys. I am having a little trouble answering this question. I am teaching myself calc 3 and am a little confused here (and thus can't ask a teacher). I need to find the limit as (x,y) approaches (0,1) of f(x,y) when f(x,y)=(xy-x)/(x^2+y^2-2y+1). Homework Equations...