Consider the series 8 n=1 (4x)n n Find the interval of convergence of this power series by first using the ratio test to find its radius of convergence and then testing the series' behavior at the endpoints of the interval specified by the radius of convergence. interval of convergence = (Enter your answer as an interval: thus, if the interval of convergence were -3 < x 5, you would enter (-3,5]. Use Inf for any endpoint at infinity.)