I said I'd been struggling with it, you added the "for some time" bit yourself

I didn't show what I'd done because I'm not even sure if I'am starting correctly, I might be thinking about this completely wrong and wanted a fresh perspective without my input.

I didn't write/create the question, just copied it out word for word, the way I read it I imagined it shaped like this:

rectangular box with square ends, the green bit being open.

I thought it would be something like:

Surface Area=2X[SUP]2[/SUP]+3XY

Volume=X[SUP]2[/SUP]Y = 4

So Y=4/X[SUP]2[/SUP]

Therefore, Surface Area=2X[SUP]2[/SUP]+3X*(4/X[SUP]2[/SUP]) which then simplifies to = 2X[SUP]2[/SUP]+(12/X)

I think I then differentiate it which would be 4X - (12/X[SUP]2[/SUP]) and this is pretty much where I got to. I haven't had a question like this before so I have no prior knowledge of something even a little like this to help me work through it, I'm just guessing here.

Sorry I haven't wrote that with the proper equation formatting like you have, I don't know how to do that on here and its 3:30am so I'll figure that out tomorrow. I know there are easier ways of getting the answer to the question but I have to use

differential calculus and show the working out involved.