Question 81911
L=W+2
AREA=L*W
16=(W+2)W
16=W^2+2W
W^2+2W-16=0
USING THE QUADRATIC EQUATION {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
WE GET:
W=(-2+-SQRT[2^2-4*1*-16])/2*1
W=(-2+-SQRT[4+64])/2
W=(-2+-SQRT68)/2
W=(-2+-8.246)/2
W=(-2+8.246)/2
W=6.246/2
W=3.123 ANSWER FOR THE WIDTH.
L=3.123+2
L=5.123 ANSWER FOR THE LENGTH.
PROOF
3.123*5.123=16
16=16