An observatory is to be in the form of a right circular cylinder surmounted by a hemispherical dome. If the hemispherical dome costs 8 times as much per square foot as the cylindrical wall what are the most economic dimensions for a volume of 6000 cubic feet?

The radius of the cylindrical base (and of the hemisphere)= ?

The height of the cylindrical base=?

So to start this I have the equation:here

sorry for having to link it, Latex isn't working for me and neither is image upload.

But I just need to know where to go from here