Dimensional reduction of non-conformal D-brane action

Question

Hi. I would like to ask about a technical detail of hep-th:0807.3324 (http://arxiv.org/pdf/0807.3324.pdf). In page 12 there is the action in the dual (string-like) frame, equation (3.1). After a while the authors say "it is straight forward to show that ... follow from an action of the form" and then there is equation(3.4).

Can someone please explain this straight forward result which to me is not as obvious? How you get from the action (3.1) to (3.4)?

Thanks a lot.