Hi I'm doing a question to find the pressure of a gas made of massless bosons. I've done everything else and now the question has resulted in me needing to evaluate this integral

This I'm pretty stuck on I've tried so far to multiply the integrand by

which gives me a second term which is easy to evaluate in terms of the zeta function but again a first term I can't seem to be able to do much with.

Any hints in the right direction would be much appreciated!

Thank you =)