Hey, I am trying to solve the problem:

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A plane with equationxa+yb+zc=1 (a,b,c>0)

together with the positive coordinate planes forms a tetrahedron of volumeV=16abc

Find the plane that minimizesVif the plane is constrained to pass through a pointP=(5,2,2) .

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Using lagrange multipliers, but cannot figure it out. Anyone know how to do it?

x/9 + y/9 + z/9 = 1 is incorrect