Question 982518
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L=length; W=width; A=Area; P=perimeter
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P=2(L+W)
38m=2(L+W)
19m=L+W
19m-L=W
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A=LW
84m^2=LW
84m^2=L(19m-L)
84m^2=19Lm-L^2
0=-L^2+19Lm-84m^2
0=L^2-19Lm+84m^2*[invoke quadratic "L", 1, -19, 84 ]
Length is 12 meters or 7 meters 
(If length is 12m, width is 7m, if length is 7m width is 12m)