I have no clue what i am doing. HELP!!!!!!!!!!!

[joslynn]

this is the problem:


A store owner wants to construct a 1000 square foot rectangular display enclosure in the store's parking lot. Three sides are to be chainlink fencing which costs $9.00 per funning foot. the fourth side is to be a brick wall which costs $18.75 per running foot. Find the dimensions that will minimize the cost.

 

[galactus]

First, identify what is known and what you need to minimize.

Area=xy, xy=1000.

Cost=9(2x+y)+18.75y

Solve the top one for, say, x; sub into bottom one; differentiate; set equal to 0 and solve.

  ***********************
  *      y chain link   *
  *                     *
  *                     *
  *   x              x  *
  * chain         chain *
  * link           link *
  *                     *
  *                     *
  *                     *
  ***********************
         y brick