MHB Solving Multivariable Problems Using Lagrange Multipliers

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The discussion focuses on solving multivariable problems using Lagrange multipliers, specifically applying them to a Cobb-Douglas production function with given parameters. Participants discuss how to derive functions for output Q based on fixed inputs of labor and capital, and the need for partial derivatives in setting up the equations. There is also mention of a graphical approach to a problem involving parallel lines and a rectangular region, suggesting a change of variables. One user shares their attempted variable substitutions for a double integral problem and seeks verification of their approach. The conversation emphasizes the application of mathematical techniques to solve complex optimization problems effectively.
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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Prove It said:
Have a read of the parallelogram problem here to help you with 14.

Double integral change of variable examples - Math Insight

I think I got it. Could you verifiy I have the correct change of variable now,

I got x = (u-v)/3 and y = (4u-v)/3
 
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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