relateing surface area to volume?

I have a problem that I can't quite figure out.

If I have a rectangular prism with a length=L width=W and hight=H and L=W, and the volume of this prism is 10,000 then you could write the volume formula as so

L(W)H=10,000

X^2(H)=10,000 because L=W and X=L=W X^2=L(W)

and surface area of the prism could be writen as so

2LW+2LH+2HW= surface area

2X^2 +2XH+2XH= surface area, Because X^2=L(W) and X=L=H

2X^2+4X= surface area

Now I have to find out what the minimum surface area would be. Do I have to use some linear optimization proces on a calculater, If so can somone give me a quick pointer, I have a TI-83. And if not, can somone show me the error of my way?