# Multivar Optimization question

1. Oct 8, 2008

### Damascus Road

Greetings,
I'm working on a problem where I am to find the coordinates of the point (x,y,z) to the plane z=3x+2y+1, which is closest to the origin.

I know that this is an optimization problem, and I believe I have to minimize (x,y,3x+2y+1).

I started by finding partial derivative, fx, of the magnitude of the function.

$$f_{x}=\frac{10x+12y+4}{2\sqrt{x^2+y^2+2x+3y+1}}$$

Setting that = 0

$$0 =\frac{10x+12y+4}{2\sqrt{x^2+y^2+2x+3y+1}}$$

now what?

Last edited: Oct 8, 2008
2. Oct 8, 2008

### Damascus Road

anyone know how to do this?

3. Oct 9, 2008

### Damascus Road

I've since solved this, although it took me a few days.
For future reference, was this the correct forum for this question? It got zero replies...

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