One side of a rectangular pen is formed by a hedge. The other three sides are made using fencing.The length of the rectangle is x metre,120 metres of fencing is available.

Question

a.show that the area of the rectangle is 1/2x*(120-x)m^2.
b.calculate the maximum posible area of the sheep pen.

Answer 1

length --- x
width ---- y
all you need is 1 length and 2 widths
x + 2y = 120
x = 120-2y

area = xy = y(120-2y) = 120y - 2y^2
d(area)/dy = 120 - 4y = 0 for a max of area
4y = 120
...

finish it up