Solving Multivariable Problems Using Lagrange Multipliers

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Discussion Overview

The discussion revolves around solving multivariable problems using Lagrange multipliers, specifically focusing on a Cobb-Douglas production function and change of variables in double integrals. Participants present problems, seek verification of their approaches, and share resources for further understanding.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents a Cobb-Douglas production function Q(L;K) = cLaKb and poses specific questions about the dependence of Q on K and L when certain variables are held constant.
  • Another participant suggests using Lagrange multipliers and mentions the need to take partial derivatives and set up scalar equations involving lambda, indicating uncertainty about the next steps.
  • A participant discusses a graphical approach to a problem involving parallel lines and a rectangular region, proposing a change of variables but expressing difficulty in its application.
  • Several participants reference external resources and threads to assist with specific problems, indicating a collaborative effort to clarify concepts.
  • One participant shares their proposed change of variables, seeking verification of its correctness.

Areas of Agreement / Disagreement

The discussion includes multiple competing views and approaches to the problems presented, with no consensus reached on the best methods or solutions. Participants express uncertainty and seek validation of their methods.

Contextual Notes

Participants' discussions involve assumptions about the functions and methods used, but these assumptions are not fully articulated. The effectiveness of the proposed changes of variables and the application of Lagrange multipliers remain unresolved.

Who May Find This Useful

This discussion may be useful for students and practitioners interested in multivariable calculus, particularly those working on optimization problems and change of variables in integration.

Vanrichten
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Ok the first problem is The output Q of an economic system subject to two inputs, such as labor L and capital K, soften modeled by the Cobb-Douglas production function Q(L;K) = cLaKb, where a; b and c
are positive real numbers. When a+b = 1, the case is called constant returns to scale. Suppose
a = 1
3 , b = 2
3 and c = 40.

A) If L is held constant at L = 10, write the function that gives the dependence of Q on K.
B) If K is held constant at K = 15, write the function that gives the dependence of Q on L

Does this look ok Name: View attachment 1681
Next I have this problem View attachment 1682

I'm pretty sure you have to use Lagrange multipliers on this one I know you first need to take partial derivatives of the function then set up the scalar equations involving lamba, I know that much but I'm stuck there.

The third problem I have is this View attachment 1683For this problem I graphed it out and you can see that there are two sets of parallel lines and the region is rectangular so I think you can use a change of variable. I tried v=y and u=2x+y but it didn't work
 

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For one possible way to solve problem 11, I recommend you read this thread:

http://mathhelpboards.com/questions-other-sites-52/emwhys-question-yahoo-questions-regarding-finding-extrema-given-region-7266.html
 

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