[填空题]
A right cylinder hasdoks i sdl8dwdb,5-l /tsl*91f j2d 3t1m tqn x+zgrki ,7g7j*6dp i0b 7vda1f height hh mm and diameter xx mm. The volume of this cylinder is equal to 7rd10ivgzg,n7 tkjxfd7ia+6 1 pb qm *$45mm^3$.
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
