The volume V(x) (in cubic units) of a rectangular box is expressed as V(x)=2x3+x2−18x−9, where x (in units) represents one of its edge lengths.
(i) Show that the box can have an integral edge length of x=3 units.
(ii) Factorise V(x) completely.
(iii) Using your factorisation, write one possible set of positive integral dimensions of the box.