[填空题]
A right cylinder has h5 s)szejoof .ja(d4o:yhb+/oeight hh mm and diameter mp1g,lpkka0fhcbi )5tt)+ (fxx mm. The volume of this cylinder is equc,kg ff0pibm51) aht +plkt)( al 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
