The circle S with center at the origin and radius 2 is given by the equation x2 + y2 = 4
The circle S have two

We have a task her that I hope someone can help us with.

The task is to build a steel frame to a tent.  The frame consists of four legs with X length and a rectangle on the top with sides Y and Z.  The lengths are measured in meters.
The volume V=X*Y*Z of the tent has to be 32 m3.  The task is to create the tent so that the total length L of the pipe is minimized to the shortest.

L=4x+2y+2z

Thx for all fast help :D

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We are a group of students trying to solve this, we can't find a way.

We are given the system of equations

ax + y +z +u =  1
  x  -y  -z +u  = -a
       y +z -au = b
  x- y +bz +u =-2a


For what values ​​of a and