Posted by craig on Wednesday, September 28, 2011 at 3:42pm.
a rectangular pen is to be constructed alongside a barn using 120 feet of fencing. the barn will be used for one side of the pen. What should the dimensions of the pen be to maximize its area.
***Can not use calculus. This is a 9th grade question

math  Steve, Wednesday, September 28, 2011 at 4:06pm
If the sides have length a and b, then, assuming b is the side parallel to the barn,
a+a+b = 120, so b = 1202a
Area = a*b = a*(1202a) = 120a  2a² = 2a(60a)
Now, this is a parabola opening downward. The vertex (a maximum) is halfway between the roots, 0 and 60, at a=30
So, pen is 30x60 feet.
Answer This Question
Related Questions
 algebra  Ian wants to build a rectangular pen for his animals. One side of the ...
 Math  A rectangular dog pen is to be constructed using a barn wall as one side ...
 Math  Manuel wants to build a rectangular pen for his animals. One side of the ...
 math  Trent wants to build a rectangular pen for his animals. One side of the ...
 Geometry  A farmer wants to fence in a rectangular pen using the wall of a barn...
 calculus optimization problem  A farmer has 460 feet of fencing with which to ...
 precalc  Old McDonald has 1000 feet of fencing, and wants to build a pen along ...
 math  a farmer has enough fencing to build 40 feet of fence. He wishes to build...
 Help please? Math 141 (PreCal) (Shapes)  Hi everyone I am lost on how to do ...
 math  Suppose you want to build an outdoor rectangular pen enclosed by fencing ...
More Related Questions