Hello, chibiusagi!

A rectangular area is to be fenced and divided into six rectangles

by one dividing fence parallel to its length and two fences parrallel to its breadth.

If the total length of fencing available is 120m fine the maxium possible area. Code:

- *-------*-------*-------*
: | | | |
y | | | |
: | | | |
- *-------*-------*-------*
: | | | |
y | | | |
: | | | |
- *-------*-------*-------*
: - x - : - x - : - x - :

The amount of fencing is: . .[1]

The area is: . 3x)(2x)\quad\Rightarrow\quad A \:=\:6xy" alt="A \:=\3x)(2x)\quad\Rightarrow\quad A \:=\:6xy" /> .[2]

Substitute [1] into [2]: .

. . And *that* is the function we must maximize.

Don't forget the dimensions of the area are: