An inflationary cosmological solution to a high-order effective gravitational field equations

An inflationary cosmological solution is found to a high-order effective gravitational field equations in ten dimensional space-time. In this solution, while the actual space scale factor expands exponentially, the internal space scale factor contracts exponentially. The parameters in the solution is compared with the ones in the literature. PACS Numbers : 04.50.+h , 98.80.cq , 98.80.Hw ,04.20.Cv