Respuesta :

width = w
length = 2w-1

Area = length * width
21 = (2w-1) * w
21 = 2w² - w
2w² - w - 21 = 0
2w² + 6w - 7w - 21 = 0
2w(w+3) - 7(w+3) = 0
(2w-7)(w+3) = 0

2w-7 = 0
w = 7/2 = 3.5 inch
length = 3.5*2 - 1 = 6 inch

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