Respuesta :

l = 4 + w 
w = w 
A = 196 m^2

A = lw
A= (4+w)w
196 = w^2 +4w

w^2 + 4w - 196 = 0

The quadratic roots (or zeros) of the function are 12 and -16. 

Since -16 does not make sense as a measure of width, then 12 is the answer.