Cosmological perturbations in a generalized gravity including tachyonic condensation

We present unified ways of handling the cosmological perturbations in a class of gravity theory covered by a general action. This gravity includes our previous generalized f(phi,R) gravity and the gravity theory motivated by the tachyonic condensation. We present a general prescription to derive the power spectra generated from vacuum quantum fluctuations in the slow-roll inflation era. An application is made to a slow-roll inflation based on the tachyonic condensation with an exponential potential.