A=(x+2)(2x+4-5)
A=(x+2)(2x-1)
A=2x^2-x+4x-2
A=2x^2+3x-2, and A=56 so
2x^2+3x-2=56
2x^2+3x=58
x^2+1.5x=29
(x+0.75)^2=29.5625
x+0.75=±√29.5625
x=-0.75+√29.5625 (only the positive root is valid as dimensions must be positive)
x≈4.69 (to nearest one-hundredth)
