Solving Lagrange Problem Near (9,12,5)

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SUMMARY

The discussion centers on solving the Lagrange problem of finding the point on the cone defined by the equation z² = x² + y² that is closest to the point (9, 12, 5). The user has derived the equations z² = x² + y², x = (9/12)y, and -2xz + 9z + 5x = 0. Participants confirm that the user is on the right track and suggest using substitution to simplify the equations further.

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navalstudent
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Hi, I am supposed to find the point on the cone z^2=x^2+y^2 which is closest to the point(9,12,5).

here is my work:

http://img27.imageshack.us/my.php?image=lagrange001.jpg

Is it correct so far?

If it is: I get stuck when trying to solve the equations z^2=x^2+y^2, x=9/12*y, and -2xz+9z+5x=0. Can someone please give me some advice?
 
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It looks to me like you are on the right track. Now use the second equation to eliminate x or y. It will work. Just keep going.
 

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