LeGrange multiplier with inequality

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SUMMARY

The discussion centers on applying the Lagrange multiplier method to maximize the volume of a box under the constraint of a perimeter limit. The function defined is f(x,y,z) = xyz, with the constraint given as 2x + 2z < 108. The user struggles with the implications of the equation xz = 0, leading to confusion about potential solutions and the feasibility of achieving maximum volume. The conclusion suggests that the problem may be misphrased, as the volume could theoretically increase indefinitely if y is allowed to grow without bounds.

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Homework Statement


Find the dimensions of the box with the largest volume, given the constraint that the perimeter of the cross sector perpendicular to length is at msot 108


Homework Equations


So I have f(x,y,z)=xyz
and the constraint is 2x+2z<108


The Attempt at a Solution


I set up the legrange multipler <yz, xz, xy>=(multiplier)<2, 0, 2>
So then you have
yz=2(multiplier)
yx=2(multiplier)
xz=0(multiplier)
and then 2x+2z<108
But since xz=0(m), I can't figure out how to solve the 4 equations to get the possible points. If I have xz=0, then either x or z is 0, right? but then there would be no volume..any ideas? Thanks!
 
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You probably have the problem stated incorrectly. As stated, the volume has no max because you could take y as large as you want no matter what x and z are.

Re-read the problem. My guess is that it will say something like "the length of the box plus the perimeter" is bounded.
 

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