Calculus 1 - Question about this tough "Related Rates" problem

Question

s3a · Answer

Hello, everyone. Problem 6, page 7 of 12 of this ( http://s3.amazonaws.com/docuum/attachments/3470/Math%20140%202008%20Exam.pdf?1261066750 ) is the problem I am stuck with, and page 20 of 32 of this ( http://s3.amazonaws.com/docuum/attachments/6949/2008-2010%20exam%20solutions.pdf?1343778569 ) document contains the solution. How is the cost function, C(x), obtained? I understand the 1/2 part, and I also understand what is being done algebraically. I just don't understand how a cost function is in area units. Could someone please explain what's going on with C(x) to me?

s3a · Answer

Actually, I solved my problem. :)

royalranger · Answer

I was just about to type lol

s3a · Answer

lol, I'm glad I saved you the time. :P :)