Suppose a farmer has 120 feet of fencing to make a rectangular barnyard enclosure. If the enclosure is x feet long, express the area A of the enclosure as a function of the length x. Briefly explain.

if length is x, then width is (120-2x)/2

Area is then length x width or
x * (60-x)

A(x) = 60x – x2

A(x) = 120x – x2

A(x) = x2 – 30x

Are any of these the answers?

The 2 meaning squared of course so

A(x) = 60x – x^2

A(x) = 120x – x^2

A(x) = x^2 – 30x

x(60-x)=60x-x^2

So A is the answer then?

A(x) = 60x – x^2

This was my first guess, was I correct?

what is the square root of negtive 80

I do not know. Does this have anything to do with my problem?