we have given the volume of cylinder and height of the cylinder .
we need to find radius .
we know the formula for volume of cylinder=[tex] \pi *r^2*h [/tex]
we know [tex] V=4\pi *x^3 cubic units [/tex]
we need to equate to find the value of height .
[tex] 4\pi *x^3=\pi *r^2*x [/tex]
[tex] 4x^2=r^2=r=2x [/tex] units
where as radius is twice the height