A rectangular parking lot has a perimeter of 820ft. The area of the Parking lot measures 42000 ft2. What is the width of the parking lot.

2W + 2L = 820

LW = 42,000 or L = 42,000/W

substitute second equation into first equation:

2W + 2 (42,000/W) = 820

2W + 84,000/W = 820

2W^2/W + 84,000/W = 820W/W

2W^2 - 820W + 84,000 = 0

quadratic formula:

W = [820 + / - SQR (672,400 - 4 (2) (84,000)) ]/2 (2)

W = [820 + / - 20]/4

W = 200, 210

using second equation:

L = 42,000/200, 42,000/210 = 210, 200

The dimensions of the parking lot are 200ft by 210ft.