(a) [tex] x^{2} [/tex] = 400
(b) [tex] \sqrt{x^2} = \sqrt{400}[/tex]
[tex]x=20,-20[/tex]
(c) Only the positive solution makes sense because you cannot have a negative side length.
(d) Since one side of the painting is 20 inches, all four sides together will be 20*4 = 80 inches
