+128475 3x meters of fencing is used for the sides and the middle fence
So.....120 - 3x is left for the top and bottom. So....the length can be expressed as
[ 120 - 3x] / 2
So....the total area A =
W * L = x ( [120 - 3x]/2 ) = (1/2)x [120 - 3x] = 60x - (3/2)x^2 =
-(3/2)x^2 + 60x
And the width, x, that maximizes the area is forund as 60 / [-2(-3/2)] =
60 / [6/2] = 60 / 3 = 20 m
And the length is 20[120 - 3(20) ] / 2 = 10 [ 120 - 60] = 10 * 60 =
600m^2
Here's a graph that shows the max area at (20, 600)
https://www.desmos.com/calculator/gzzu0hnyz1
