For length: 0 < x <10; For width: 0 < x+ 1 < 8: 0 < x < 7.
(2) The area of a hexagon is equal to the sum of the areas of six faces, that is, three faces.
S rectangle ABCD= 10×8=80, s rectangle ABB*A*=8×√x? +(x+ 1)？ =8√2x？ +2x+ 1，
S rectangle ADD*A*= 10×√x? +(x+ 1)？ = 10√2x？ +2x+ 1, the total area multiplied by 2.
So the total area s is always = 160+36√2x? +2x+ 1(cm？ )。
(3) The conclusion has not changed, because the conclusion of (2) is to calculate the total area of a cuboid. You draw a picture without overlap and continue to calculate the total area. The ideas and methods are exactly the same, so the result will not change!
The second small step may be ugly. I attached my own writing process, which should be understandable. I hope you can pass the exam. I don't know how to ask questions!