Two related type of questions:
1) A rectangular prismic net enclosure for practising golf shots is open at one end. Find the dimensions that will minimize the amount of netting needed and give a volume of 144 m3. Netting is only required on the sides, top, and the far end. Height is x, width is also x, and length is y.
2) A rectangular piece of land is to be fenced using two kinds of fencing. Two opposite sides will be fenced using $6/m fencing, while the other two sided will require $9/m fencing. What are the dimensions of the rectangular lot of greatest area that can be fenced for a cost of $9000?
A'(x) = 0 for max/min
The Attempt at a Solution
In both questions, I don't know what to do with the 144m3 or the $9000.
What equations am I supposed to use? I could also use tips on how to make equations for these types of questions.