math
posted by brit on .
A farmer plans to enclose a rectangular region, using part of his barn for one side and fencing for the other three sides. If the side parallel to the barn is to be twice the length of an adjacent side, and the area of the region is to be 512 ft2, how many feet of fencing should be purchased?

make a sketch,
label the two shorter sides x
and the one longer side 2x (it is twice as long)
so x(2x) = 512
2x^2 = 512
x^2 = 256
x = √256 = 16
so he needs 3x of fencing or 48 feet