Inflationary phase in Generalized Brans-Dicke theory

We find a solution for exponential inflation in a Brans-Dicke generalized model, where the coupling "constant " is variable. While in General Relativity the equation of state is p is equal to minus rho, here we find p proportional to rho, where the proportionality constant is smaller than -2/3. The negativity of cosmic pressure implies acceleration of the expansion, even with lambda < 0 >.