Solving quadratic equation help

Determine The maximum area of a rectangular field that can be enclosed by 2400 of fencing.

I think I have to use the quadratic formula.

The answer is a square, which is a special case of a rectangle.

2400/4 = 600 , one side of the square.

600² = 360,000 units², maximum area.
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a square is a special rectangle

let say you have 16 ft to make a fence

2(L + W) = P
2(L + W) = 16
L + W = 8

LW = A
1 * 7 = 7 FT^2
2 * 6 = 12 FT^2
3 * 5 = 15 FT^2
4 * 4 = 16 FT^2 ******
5 * 3 = 15 FT^2
6 * 2 = 12 FT^2
7 * 1 = 7 FT^2

Max Area will be a square
4s = 16
s = 4

s^2 = A
4^2 = A
16 ft^2 = A

4s = P
4s = 2400
s = 600

s^2 = A
600^2 = A
360,000 ft^2 = A