Tough Optimization Question

Can someone send me the full steps so i can learn from it, i missed the lecture today so i didn't get the step by step walk through of the solution :( i'm having such a hard time with the optimization unit it's really tough... and our textbooks only give us to answer so i have no idea how to solve the question.

it's #6

http://smcewen.pbworks.com/f/Sec3_3+Extra+Practice.pdf

Re: Tough Optimization Question

Your restriction is the the volume must be 240

The volume in each box is given by so

The area of wire that is needed is the sum of the surface areas

Let

You want to minimise A so first get A in terms of only x, then find when equals zero, confirm that it is a minimum for the area not a maximum. You will probably get 2 answers, remember than you are restricted in how big/small x can be.