[填空题]
A right cylinder has height hh mm and diadq5rx e5rq112hbg5sb metells qq;gqa/ .ks 4e88pr xx mm. The volume of this cylinder is 4 sllsq;8q q k/.apg8eequal to $45mm^3$.
The total surface area, A, of the cylinder can be expressed as $A = \frac{\pi}{2}x^2 + \frac{k}{x}$.
1.Find the value of k.k=
2.Find the value of x that makes the total surface area a minimum.x= mm