math
posted by melissa on .
a farmer is building a fence around his yard. one side of the fence will be the side of his barn , the other three sides will be made of wood. He has enough materials for 120m of fence, what is the maximum area he can enclose ? what are the dimensions which give this area

Let x is the side of the barn.
The area of the yard
A(x)=x*(120x)/2=60xx^2/2
A'(x)=60x=0 => x=60,(120x)/2=30
max A=1800m^2