Question

You have 100 feet of fencing and decide to make a rectangular garden. What is the largest area enclosed

Answer 1

Answer:

625 ft^2

Step-by-step explanation:

Given

$P = 100$ --- perimeter

Required

The largest area

The perimeter is calculated as:

$P = 2 * ( L + W)$

So, we have:

$2 * ( L + W) = 100$

Divide both sides by 2

$L + W = 50$

Make  L the subject

$L = 50 - W$

The area is calculated as:

$A= L * W$

Substitute $L = 50 - W$

$A= (50 - W) * W$

Open bracket

$A = 50W - W^2$

Differentiate with respect to W

$A' = 50 -2W$

Set to 0; to get the maximum value of W

$50 - 2W = 0$

Collect like terms

$-2W = -50$

Divide by -2

$W = 25$

So, the maximum area is:

$A = 50W - W^2$

$A = 50 * 25 - 25^2$

$A = 1250 - 625$

$A = 625$