You should first plot it to know what the volume looks like.
The volume between z=1 and z=2 is that of a circular disk. You need to use cylindrical coordinates.
Description of the region:
For r and θ fixed, z varies from z=1 to z=2
For θ fixed, r varies from r=1 to r=√2
θ varies from θ=0 to θ=2∏
Plug the limits into the triple integral and evaluate to find the required volume:
[tex]\int \int \int dr d\theta dz[/tex]