Question

Beth has 4900 feet of fencing available to enclose a rectangular field. one side of the field lies along a river, so only three sides require fencing. express the area a of the rectangle as a function of x, where x is the length of the side parallel to the river.

Answer 1

Perimeter (P) = 2L + x

            4900 = 2L + x   ⇒  4900 - x = 2L  ⇒ $\frac{4900 - x}{2}$ = L

Area (A) = L · x

A  = ($\frac{4900 - x}{2}$) (x)

    = $\frac{4900x - x^2}{2}$