Multivar Optimization question

[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?

 

[Damascus Road]

anyone know how to do this?

 

[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...