Answer
Center is $(0,3,-4 )$ and radius is $5$
Work Step by Step
As we know the standard equation of sphere is $(x-a)^2+(y-b)^2+(z-c)^2=r^2$
where $(a,b,c)$ represents center and radius of the sphere is $r$
Given: $x^2+y^2+z^2-6y+8z=0$
This can be written as: $x^2+y^2-6y+z^2+8z=0 \implies x^2+(y-3)^2+(z+4)^2=0+9+16$
or, $x^2+(y-3)^2+(z+4)^2=25 \implies (x -0)^2+(y-3)^2+(z-(-4))^2=5$
Thus, we have
Center is $(0,3,-4 )$ and radius is $5$