Max area

[chjopl]

What are the dimensions of a rectangular plot with maxium area if the north and south sides cost twice as much to fence as the east and west sides and if you have $1000 to spend? East and west sides cost $10 per meter to fence.

[arildno]

Let "x" be the length in the eastern direction, "y" the length in the northern direction.

Hence, the total cost satisfies:
10*(2x)+20*(2y)=1000
Or:
x=50-2y

You are to maximize x*y