Аннотация:We consider F(R) cosmological models with a scalar field. For the R^2 model in the spatially flat Friedmann–Lemaitre–Robertson–Walker metric, the Ricci scalar R can smoothly change its sign during the evolution if and only if the scalar field is a phantom one. In the Bianchi I metric, the Ricci scalar cannot smoothly change its sign if the corresponding solution is anisotropic at R=0. This result does not depend on the type of the scalar field. In the Bianchi I metric, the general solution of evolution equations has been obtained.