November 16th, 2008, 11:27 AM  #1 
Newbie Joined: Nov 2008 Posts: 1 Thanks: 0  Lagrange Multiplier Fix..
Hi, I'm in the midst of revision for a calculus exam next week. I'm not sure if I tackled this problem correctly. Find the maximum and minimum distances from the origin for points on the curve described by 3x^2 + 2y^2 + z^2 = 20 and z^2 = 2xy . I know the constraint eqns defined by g(x,y,z)= 3x^2 + 2y^2 + z^2  20 = 0 and h(x,y,z)= z^2 = 2xy Also I define the function f(x,y,z)= x^2 + y^2 + z^2, which I have to find the minimum and maximum values for. In short, what I did was to introduce a function F(x,y,z,k,j) = f(x,y,z)  k[g(x,y,z)]  j[h(x,y,z)] and solve for grad(F)=0 ( k and j are constants) The problem is when I realised 1 of the constants I had used turns out to be 0, is that correct? PLEASE, would really appreciate some guidance on this: my ans is minimum: (sqrt(13/, 0, 0) and max: (sqrt(13/, 0, 0) Will be glad to countercheck with some of your answers 

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fix, lagrange, multiplier 
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